Add post tags, with a tag page and two side-column modules

Posts can now carry tags, set on the post form as a checklist of the
blog's existing tags plus a comma-separated box for new ones (no JS).
A tag is a name and a unique slug, so "Go" and "go" are one tag and
Greek tags get readable URLs; tags no post uses any more are deleted.

On the blog, tags appear under the post date and link to /tag/<slug>,
which lists the published posts from every page, paginated like a page.
Two new layout modules show them: a Tags list (with counts, by use) and
a Tag cloud (alphabetical, sized by use). Both are only fetched when a
visible module needs them.

The article loop and pager move to a shared postlist partial; while
there, the pager stops adding a trailing slash — /news/?p=2 was a 404
because a {page} wildcard never matches one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

1 files changed, 1 insertions, 1 deletions

diff --git a/internal/web/handlers_pages.go b/internal/web/handlers_pages.go
index 3b128e0..bc74f71 100644
--- a/internal/web/handlers_pages.go
+++ b/internal/web/handlers_pages.go
@@ -13,7 +13,7 @@ import (
 
 // Page slugs that would collide with blog routes, or with management routes on the root domain.
 var reservedPageSlugs = map[string]bool{"media": true, "static": true, "feed.xml": true, "favicon.ico": true,
-	"webadmin": true, "logout": true, "dashboard": true, "account": true, "admin": true, "b": true, "healthz": true}
+	"webadmin": true, "logout": true, "dashboard": true, "account": true, "admin": true, "b": true, "healthz": true, "tag": true}
 
 func (s *Server) handlePages(w http.ResponseWriter, r *http.Request) {
 	pages, err := blogStore(r).ListPages(r.Context())