Add configurable post types

[compscidr]

Summary

• Adds a PostType model so admins can create custom content types (e.g. Notes, Links, Recipes), each with its own URL namespace (/notes/2024/01/15/slug) and automatic listing page (/notes)
• The default type is "Post" with slug "posts", preserving all existing URLs and backward compatibility
• Writing pages can optionally filter by a specific post type via admin dropdown

Changes

• New model: PostType with name, slug, description
• Post model: Added PostTypeID foreign key; Permalink() and Adminlink() use type slug
• Page model: Added optional PostTypeID for writing page filtering
• Routing: NoRoute resolves type-prefixed URLs (/{type}/{yyyy}/{mm}/{dd}/{slug}) and admin equivalents
• Admin: Full PostType CRUD (create, edit, delete with referential integrity), post type dropdown on post create/edit, post type filter on writing page edit
• Migration: Seeds default "Post" type, assigns existing posts, links writing pages to their post type
• Templates: 4 new templates, 7 modified with Post Types nav link and dropdowns
• JS: Updated redirects to use type-aware URLs
• Tests: Updated across all packages (admin, blog, tools)

Test plan

• Existing post URLs (/posts/2024/01/15/slug) work unchanged
• Admin can create a new post type (e.g. "Notes" with slug "notes")
• Posts can be reassigned to a different type and save correctly
• /notes shows a listing of only "Notes" type posts
• /notes/2024/01/15/my-note resolves correctly
• Writing page filter dropdown shows saved value and filters posts accordingly
• Slug conflicts between post types and pages are rejected
• Deleting a post type with posts is rejected
• go test ./... passes

Closes #165

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 32.86119% with 237 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.72%. Comparing base (ec471d4) to head (d776b93).

Files with missing lines	Patch %	Lines
blog/blog.go	13.19%	120 Missing and 5 partials ⚠️
admin/admin.go	40.46%	75 Missing and 28 partials ⚠️
tools/migrate.go	73.07%	4 Missing and 3 partials ⚠️
blog/post_type.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #484      +/-   ##
==========================================
- Coverage   47.60%   45.72%   -1.88%     
==========================================
  Files           7        8       +1     
  Lines        1689     1999     +310     
==========================================
+ Hits          804      914     +110     
- Misses        811      975     +164     
- Partials       74      110      +36     

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[Copilot]

Pull request overview

Adds a configurable PostType concept to support multiple content types (e.g., Notes/Links) with their own URL namespaces and listing pages, while keeping the default posts URLs backward-compatible.

Changes:

• Introduces PostType model + admin CRUD and UI wiring (dropdowns, navigation).
• Updates post/page models, routing (type-prefixed URLs + listing pages), and sitemap generation.
• Extends migrations and tests to seed/attach the default posts type and validate the new behavior.

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
www/js/admin-script.js	Sends post_type_id in create/update payloads and redirects to type-aware URLs.
tools/migrate_test.go	Adds assertions that the default post type is seeded and writing pages are linked.
tools/migrate.go	Migrates PostType, seeds the default type, links writing pages, and updates internal-link regex.
templates/post_type_listing.html	New listing template for a post type (/{typeSlug}).
templates/post-admin.html	Adds post type selector to the post edit view.
templates/admin_settings.html	Adds “Post Types” link to admin nav.
templates/admin_post_types.html	New admin listing/create/delete UI for post types.
templates/admin_pages.html	Adds “Post Types” link to admin nav.
templates/admin_new_post.html	Adds post type dropdown on the new post form.
templates/admin_edit_post_type.html	New admin edit UI for a single post type.
templates/admin_edit_page.html	Adds optional writing-page post type filter and saves post_type_id.
templates/admin_dashboard.html	Adds “Post Types” link to admin nav.
templates/admin_all_posts.html	Shows post type name in the all-posts table and adds nav link.
templates/admin.html	Adds “Post Types” link to admin nav.
goblog.go	Registers post type CRUD API routes and admin HTML routes.
blog/post_type.go	Adds the PostType model and its listing permalink helper.
blog/post_test.go	Updates permalink/adminlink tests for type-aware URLs.
blog/post.go	Adds PostTypeID/relation and makes permalinks/adminlinks type-aware.
blog/page.go	Adds optional PostTypeID to pages (writing-page filtering).
blog/blog_test.go	Updates migrations/seeding and adds routing coverage for type-prefixed URLs.
blog/blog.go	Preloads PostType, adds post type lookup/listing rendering, routing resolution, and sitemap entries.
admin/admin_test.go	Adds post type CRUD API + HTML route coverage and seeds default type in tests.
admin/admin.go	Implements post type CRUD endpoints, adds slug conflict checks, and wires post type data into admin views and post create/update.

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