fix: Update folder collections to work without frontmatter

- Removed format: yaml-frontmatter requirement
- Added identifier_field: name to use filename
- Added summary: {{filename}} to display filename in list
- Simplified fields to just body/content

This allows existing markdown files without YAML frontmatter to be edited.

admin/config.yml

@@ -43,10 +43,9 @@ collections:
     folder: "docs/planning"
     create: true
     extension: "md"
-    format: "yaml-frontmatter"
+    identifier_field: "name"
+    summary: "{{filename}}"
     fields:
-      - {label: "Title", name: "title", widget: "string"}
-      - {label: "Date", name: "date", widget: "datetime"}
       - {label: "Content", name: "body", widget: "markdown"}
 
   - name: "milestones"
@@ -54,9 +53,9 @@ collections:
     folder: "docs/milestones"
     create: true
     extension: "md"
-    format: "yaml-frontmatter"
+    identifier_field: "name"
+    summary: "{{filename}}"
     fields:
-      - {label: "Title", name: "title", widget: "string"}
       - {label: "Content", name: "body", widget: "markdown"}
 
   - name: "implementation"
@@ -64,7 +63,7 @@ collections:
     folder: "docs/implementation"
     create: true
     extension: "md"
-    format: "yaml-frontmatter"
+    identifier_field: "name"
+    summary: "{{filename}}"
     fields:
-      - {label: "Title", name: "title", widget: "string"}
       - {label: "Content", name: "body", widget: "markdown"}