feat: warm palette overhaul — cold zinc/teal to warm stone/amber

Replace the entire color system with a design-driven warm palette:

- Surface tokens: cold zinc grays → warm stone (#faf8f5 to #0f0e0d)
- Accent tokens: cold teal → warm amber (#fffbeb to #451a03)
- All bg-white → bg-surface-50 across templates (warm cream instead of pure white)
- Critical CSS: all hardcoded hex values updated to warm palette
- Prism code blocks: cold gray backgrounds → warm stone
- Pagefind search UI: blue buttons/links → amber interactive colors
- Dark mode: warm dark surfaces with amber accents throughout

Design system documented in .interface-design/system.md

Confab-Link: http://localhost:8080/sessions/bd3f7012-c703-47e9-bfe2-2ad04ce1842d

_includes/components/sidebar.njk

@@ -65,7 +65,7 @@
       class="widget-collapsible mb-4"
       x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : {{ defaultOpen }} }"
     >
-      <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden {{ widgetBorder }}">
+      <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden {{ widgetBorder }}">
         <button
           class="widget-header w-full p-4"
           @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)"
@@ -156,7 +156,7 @@
   {# Author Card (h-card) — always shown #}
   {% set widgetKey = "listing-fb-author-card" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : true }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("user", "w-5 h-5 text-surface-500") }} Author</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -170,7 +170,7 @@
   {# Social Activity — Bluesky/Mastodon feeds #}
   {% set widgetKey = "listing-fb-social-activity" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : true }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-[#0085ff]">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-[#0085ff]">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("globe", "w-5 h-5 text-[#0085ff]") }} Social Activity</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -184,7 +184,7 @@
   {# GitHub Repos #}
   {% set widgetKey = "listing-fb-github-repos" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : true }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-surface-400 dark:border-l-surface-500">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-surface-400 dark:border-l-surface-500">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("github", "w-5 h-5 text-surface-800 dark:text-surface-200") }} GitHub</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -198,7 +198,7 @@
   {# Funkwhale — Now Playing / Listening Stats #}
   {% set widgetKey = "listing-fb-funkwhale" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-purple-400 dark:border-l-purple-500">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-purple-400 dark:border-l-purple-500">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("headphones", "w-5 h-5 text-purple-500") }} Listening</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -212,7 +212,7 @@
   {# Recent Posts #}
   {% set widgetKey = "listing-fb-recent-posts" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("list", "w-5 h-5 text-surface-500") }} Recent Posts</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -227,7 +227,7 @@
   {% if blogrollStatus and blogrollStatus.source == "indiekit" %}
   {% set widgetKey = "listing-fb-blogroll" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-amber-400 dark:border-l-amber-500">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-amber-400 dark:border-l-amber-500">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("book-open", "w-5 h-5 text-amber-500") }} Blogroll</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -243,7 +243,7 @@
   {% if blogrollStatus and blogrollStatus.source == "indiekit" %}
   {% set widgetKey = "listing-fb-feedland" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-amber-400 dark:border-l-amber-500">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden border-l-[3px] border-l-amber-400 dark:border-l-amber-500">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("rss", "w-5 h-5 text-amber-500") }} FeedLand</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -258,7 +258,7 @@
   {# Recent Comments #}
   {% set widgetKey = "listing-fb-recent-comments" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("chat", "w-5 h-5 text-surface-500") }} Recent Comments</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>
@@ -272,7 +272,7 @@
   {# Categories/Tags #}
   {% set widgetKey = "listing-fb-categories" %}
   <div class="widget-collapsible mb-4" x-data="{ open: localStorage.getItem('{{ widgetKey }}') !== null ? localStorage.getItem('{{ widgetKey }}') === 'true' : false }">
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
+    <div class="bg-surface-50 dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 shadow-sm overflow-hidden">
       <button class="widget-header w-full p-4" @click="open = !open; localStorage.setItem('{{ widgetKey }}', open)" :aria-expanded="open ? 'true' : 'false'">
         <h3 class="widget-title font-bold text-lg flex items-center gap-2">{{ icon("tag", "w-5 h-5 text-surface-500") }} Categories</h3>
         <svg class="widget-chevron" :class="open && 'rotate-180'" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7"/></svg>