feat: comprehensive blog example with module-based component layout

[jackielii]

Summary

Adds examples/blog/ — a full blog (public reader + admin CMS) organized as per-feature Go packages with shared ui/ packages, mirroring the layout you'd reach for in a typical React/Next app. Replaces the never-merged single-package attempt in PR #2; please close that one when this lands.

Why a new example

None of the existing examples use WithArgs DI, page-level Middlewares(), a custom error handler, deep nested routes, or cross-package component composition. This one does — and demonstrates them in a coherent app rather than a contrived snippet.

What it shows

Pattern	Where
Per-feature Go packages (blog/, admin/) + shared ui/layout, ui/components	tree
Cross-package component composition with one-way import direction	every .templ
Ref("loginPage") for cross-feature links to avoid import cycles	ui/layout/layout.templ
Nested route hierarchies, 3 levels (/admin/posts/{id}/edit)	admin/routes.go, admin/posts.go
WithArgs(store, authSvc) consumed by Props/ServeHTTP/Middlewares	main.go + every Props
Page-level Middlewares() returning RequireAdmin (with DI)	admin/routes.go
Props(r, target RenderTarget, *store.Store) with conditional widget loads	admin/dashboard.templ, blog/search.templ
Standalone function components as HTMX targets via target.Is(StatsGrid) then RenderComponent	admin/dashboard.templ, admin/components.templ
Page() + Content() split for HTMX #content swaps	blog/home.templ, admin/dashboard.templ
ServeHTTP form handlers — redirect for non-HTMX, RenderComponent(...) partial for HTMX	blog/comment.go, admin/posts.go
WithErrorHandler rendering a styled cross-package error component (full doc + HTMX block)	main.go + ui/components
URLFor with path params + query-string templates []any{p, "?page={page}"}	blog/category.templ
ID/IDTarget wiring for hx-target	throughout

App features

• Public reader: home, post detail, category archive with pagination, fuzzy search, comments
• Admin CMS: cookie-session auth (admin/admin), dashboard with two HTMX-refreshed widgets (StatsGrid, RecentPostsCard), post + user CRUD
• In-memory store seeded at boot; Tailwind via Play CDN — no asset pipeline

Notes for reviewers

• Login placement is non-obvious: admin.LoginPage is mounted as a sibling of admin.Pages (not a child) because admin.Pages.Middlewares() returns RequireAdmin, which would otherwise gate the login form itself.
• Admin POST routes use explicit verbs (/posts/create, /posts/{id}/update, /posts/{id}/delete) instead of POST /posts/{id} to avoid Go's ServeMux conflict with literal segments like /posts/new.
• README explicitly lists what's omitted vs production (plaintext passwords, no CSRF, in-memory sessions, etc.).

Test plan

• go vet ./... at repo root — clean
• templ generate -include-version=false && go build ./... && go vet ./... in examples/blog/ — clean
• go test ./... at repo root — framework tests still pass
• Public reader: /, /posts/welcome, /categories/guides?page=1, /search?q=props all 200
• Custom 404 on /posts/nope; HTMX HX-Request returns just ErrorBlock (301 bytes) vs full ErrorPage (~1KB)
• Auth gating: unauthenticated /admin/ 303s to /admin/login; correct creds 303 to /admin/; logout invalidates session
• HTMX widget refresh: HX-Target: stats-grid → 906 bytes (just widget); recent-posts-card → 1409 bytes; content → body fragment (3218 bytes); full doc → 4259 bytes
• Comment form: HTMX POST returns refreshed CommentsList with new comment
• Post CRUD: edit form prefilled, update redirects, HTMX delete refreshes PostsTable partial
• Search: HTMX HX-Target: search-results returns just the results div

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.65%. Comparing base (67e5283) to head (646f896).

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #5   +/-   ##
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  Coverage   96.65%   96.65%           
=======================================
  Files          13       13           
  Lines        1197     1197           
=======================================
  Hits         1157     1157           
  Misses         26       26           
  Partials       14       14           

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