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

.interface-design/system.md

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+# Design System — rmendes.net
+
+## Direction: Workshop Terminal
+
+**Feel:** A well-configured terminal in a warm room. Structure is precise and technical. Warmth comes from surfaces and content, not decorative color. Color is signal, not decoration.
+
+**Signature:** Chromatically quiet at rest, vivid in context. The base is warm monochrome. Color enters when content demands it — music pages glow purple, code pages pulse emerald, social feeds carry brand colors. You feel the shift as you navigate between worlds.
+
+## Intent
+
+**Who:** Visitors to a DevOps engineer's personal site — peers, recruiters, fellow IndieWeb enthusiasts, RSS subscribers. They're reading, browsing, discovering.
+
+**What:** Read posts, explore interests, follow feeds, understand who this person is.
+
+**How it should feel:** Like opening a well-used notebook in a workshop. Technical precision meets personal warmth. Not corporate, not cold, not decorative.
+
+## Surfaces — Warm Stone
+
+Warm neutral tones. Not yellow — just not cold. The difference is felt, not seen.
+
+| Token | Light | Dark | Role |
+|-------|-------|------|------|
+| 50 | `#faf8f5` | — | Canvas background |
+| 100 | `#f4f2ee` | — | Card surfaces |
+| 200 | `#e8e5df` | — | Borders, dividers |
+| 300 | `#d5d0c8` | — | Strong borders |
+| 400 | `#a09a90` | — | Muted/placeholder text |
+| 500 | `#7a746a` | — | Secondary text |
+| 600 | `#5c5750` | — | — |
+| 700 | `#3f3b35` | — | Dark text secondary |
+| 800 | `#2a2722` | — | Card surfaces (dark) |
+| 900 | `#1c1b19` | — | Canvas (dark) |
+| 950 | `#0f0e0d` | — | Deepest dark |
+
+## Text Hierarchy
+
+| Level | Light | Dark | Usage |
+|-------|-------|------|-------|
+| Primary | surface-900 `#1c1b19` | surface-50 `#faf8f5` | Headlines, body |
+| Secondary | surface-600 `#5c5750` | surface-400 `#a09a90` | Supporting text |
+| Muted | surface-400 `#a09a90` | surface-600 `#5c5750` | Metadata, timestamps |
+| Faint | surface-300 `#d5d0c8` | surface-700 `#3f3b35` | Disabled, decorative |
+
+## Interactive — Accent (Warm Amber)
+
+Default interactive color for generic links, CTAs, focus rings. Terminal amber warmth.
+
+| Weight | Value | Usage |
+|--------|-------|-------|
+| 400 | `#fbbf24` | Dark mode links, hover states |
+| 500 | `#f59e0b` | — |
+| 600 | `#d97706` | Light mode links, buttons |
+| 700 | `#b45309` | Light mode hover |
+
+## Domain Colors
+
+Each section of the site owns its chromatic identity. These override accent on their respective pages.
+
+| Domain | Tailwind Color | Pages |
+|--------|---------------|-------|
+| Writing/Blog | amber (= accent) | blog, articles, notes, homepage |
+| Code/GitHub | emerald | github, repo widgets |
+| Music | violet | funkwhale, listening, last.fm |
+| Bluesky | `#0085ff` | social-activity bluesky tab |
+| Mastodon | `#a730b8` | social-activity mastodon tab |
+| Bookmarks | amber | bookmarks page |
+| Likes | rose | likes page |
+| Replies | sky | replies page |
+| Reposts | emerald | reposts page |
+| Photos | violet | photos page |
+| RSS/Podcasts | orange | podroll, subscribe, RSS links |
+| CV | neutral (no accent) | cv page |
+
+## Typography
+
+- **Body:** Inter — clean, technical sans-serif
+- **Metadata:** `font-mono` for dates, timestamps, stats, version numbers
+- **Headlines:** Inter bold, tight tracking
+
+## Depth Strategy
+
+**Borders only.** No drop shadows. Low-opacity warm borders define surfaces. Hierarchy comes from surface color shifts, not elevation effects.
+
+## Spacing
+
+Base: 4px (Tailwind default). No custom scale needed.
+
+## Dark Mode
+
+- Surfaces invert (dark warm canvas, lighter warm cards)
+- Domain colors use their 400-weight for dark mode (lighter/brighter)
+- Borders use warm low-opacity rgba
+- No shadows in either mode