feat: add gardenStage and ai fields to all post type presets

- gardenStage: added to all post types (article, note, bookmark, like,
  repost, photo, reply, page) so Indiekit preserves it in frontmatter
- aiTextLevel/aiCodeLevel/aiTools/aiDescription: extended from article+note
  to all content post types (bookmark, repost, photo, reply, page)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

indiekit.config.mjs

@@ -213,6 +213,7 @@ export default {
           url: `${publicationBaseUrl}/articles/{slug}/`,
         },
         fields: {
+          gardenStage: {},
           aiTextLevel: {},
           aiCodeLevel: {},
           aiTools: {},
@@ -226,6 +227,7 @@ export default {
           url: `${publicationBaseUrl}/notes/{slug}/`,
         },
         fields: {
+          gardenStage: {},
           aiTextLevel: {},
           aiCodeLevel: {},
           aiTools: {},
@@ -238,6 +240,13 @@ export default {
           path: "content/bookmarks/{slug}.md",
           url: `${publicationBaseUrl}/bookmarks/{slug}/`,
         },
+        fields: {
+          gardenStage: {},
+          aiTextLevel: {},
+          aiCodeLevel: {},
+          aiTools: {},
+          aiDescription: {},
+        },
       },
       like: {
         name: "Like",
@@ -245,6 +254,9 @@ export default {
           path: "content/likes/{slug}.md",
           url: `${publicationBaseUrl}/likes/{slug}/`,
         },
+        fields: {
+          gardenStage: {},
+        },
       },
       repost: {
         name: "Repost",
@@ -252,6 +264,13 @@ export default {
           path: "content/reposts/{slug}.md",
           url: `${publicationBaseUrl}/reposts/{slug}/`,
         },
+        fields: {
+          gardenStage: {},
+          aiTextLevel: {},
+          aiCodeLevel: {},
+          aiTools: {},
+          aiDescription: {},
+        },
       },
       photo: {
         name: "Foto",
@@ -263,6 +282,13 @@ export default {
           path: "images/{filename}",
           url: `${publicationBaseUrl}/images/{filename}`,
         },
+        fields: {
+          gardenStage: {},
+          aiTextLevel: {},
+          aiCodeLevel: {},
+          aiTools: {},
+          aiDescription: {},
+        },
       },
       reply: {
         name: "Antwort",
@@ -270,6 +296,13 @@ export default {
           path: "content/replies/{slug}.md",
           url: `${publicationBaseUrl}/replies/{slug}/`,
         },
+        fields: {
+          gardenStage: {},
+          aiTextLevel: {},
+          aiCodeLevel: {},
+          aiTools: {},
+          aiDescription: {},
+        },
       },
       page: {
         name: "Seite",
@@ -277,6 +310,13 @@ export default {
           path: "content/pages/{slug}.md",
           url: `${publicationBaseUrl}/{slug}/`,
         },
+        fields: {
+          gardenStage: {},
+          aiTextLevel: {},
+          aiCodeLevel: {},
+          aiTools: {},
+          aiDescription: {},
+        },
       },
     },
   },