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.

frontend/server/routes/content/articles/index.get.ts

@@ -0,0 +1,42 @@
+import type { ArticleSummary, Category, Paginated } from '#shared/types/blog'
+
+interface RawArticleSummary {
+  id: string
+  title: string
+  slug: string
+  publishedAt: string
+  cover: string
+  coverAlt: string | null
+  expand?: { category?: Category }
+}
+
+function toSummary(raw: RawArticleSummary): ArticleSummary {
+  return {
+    title: raw.title,
+    slug: raw.slug,
+    publishedAt: raw.publishedAt,
+    cover: toMediaImage('articles', raw.id, raw.cover, raw.coverAlt),
+    category: raw.expand?.category ?? null,
+  }
+}
+
+export default defineEventHandler(async (event): Promise<Paginated<ArticleSummary>> => {
+  const query = getQuery(event)
+  const page = pageParam(query.page)
+  const category = typeof query.category === 'string' ? query.category : null
+
+  const filter = category
+    ? `&filter=${encodeURIComponent(`category.slug = ${quote(category)}`)}`
+    : ''
+
+  const response = await pbFetch<PbList<RawArticleSummary>>(
+    `/api/collections/articles/records?fields=${ARTICLE_SUMMARY_FIELDS}&expand=category&sort=-publishedAt&${pagination(page)}${filter}`
+  )
+
+  return {
+    items: response.items.map(toSummary),
+    page: response.page,
+    pageCount: response.totalPages,
+    total: response.totalItems,
+  }
+})