Replace Strapi CMS with PocketBase

Strapi + Postgres are gone in favor of PocketBase: a single Go binary
with embedded SQLite, built-in admin UI and per-collection API rules.
No content existed yet, so this is a clean swap with no data migration.

Collections and rules are defined as code in pocketbase/pb_migrations/
and applied automatically on first boot. Draft & Publish has no native
PocketBase equivalent, so it's reproduced with a nullable `publishedAt`
field enforced by listRule/viewRule, matching the old Strapi semantics.

Routing flips: PocketBase's admin UI and REST/file API are hardwired to
`/_/` and `/api/*` at the domain root (its own dashboard assets and API
calls reference those paths directly, so a stripped path prefix like
`/admin/*` would break them). `/api` is therefore reserved for
PocketBase now, and the frontend's Nitro endpoints move to `/content/*`
(frontend/server/routes/content/, not server/api/). A `/admin` vanity
route in Nitro (not Caddy) redirects to `/_/`, so it works the same in
dev, where Caddy isn't part of the stack, and in production.

frontend/server/utils/strapi.ts becomes pocketbase.ts; queries.ts is
rewritten for PocketBase's filter/sort/fields/expand query syntax.
StrapiImage becomes MediaImage (no width/height — PocketBase file
fields don't store dimensions, and the cover images already reserve
their aspect ratio via CSS, so this is not a regression).

docs/*.md, CLAUDE.md and README.md are updated in the same commit.

caddy/Caddyfile

@@ -16,24 +16,23 @@
 	import security_headers
 	encode zstd gzip
 
-	# Strapi mounts each of its (and its plugins') admin APIs at its own
-	# top-level path, not all under /admin - the admin panel's dashboard
-	# widgets, media library, i18n, etc each call their own plugin prefix.
-	# This list is every @strapi/* package in cms/package.json plus the
-	# core-bundled plugins (content-manager, content-type-builder, upload,
-	# i18n, email, content-releases, review-workflows). Adding a new Strapi
-	# plugin later means adding its prefix here too.
-	# None of this touches /api, reserved for the frontend's own Nitro
-	# endpoints.
-	@cms path /admin* /content-manager* /content-type-builder* /upload*\
-		/i18n* /email* /content-releases* /review-workflows*\
-		/users-permissions* /cloud*
-	handle @cms {
-		# Uploaded media can be large; Strapi's own limit still applies.
+	# /admin is a vanity redirect to /_/, PocketBase's own fixed dashboard
+	# route — handled by Nitro (frontend/server/routes/admin.get.ts), not
+	# here, so it also works in dev where Caddy isn't in the stack.
+
+	# PocketBase's admin UI (/_/) and its own REST/file API (/api/*) both
+	# reference themselves with root-absolute paths, so they must be
+	# reachable unprefixed at the domain root — a path like /admin/api/...
+	# with a stripped prefix would break the dashboard's own asset and API
+	# calls. This is why the frontend's Nitro endpoints live under
+	# /content/*, not /api/*: /api is reserved for PocketBase here.
+	@pocketbase path /_/* /api/*
+	handle @pocketbase {
+		# Cover images and admin uploads pass through here too.
 		request_body {
 			max_size 100MB
 		}
-		reverse_proxy cms:1337
+		reverse_proxy pocketbase:8090
 	}
 
 	handle {