refactor: replace Meilisearch with PostgreSQL full-text search

Remove Meilisearch dependency entirely. Search is now handled by
PostgreSQL ILIKE with pg_trgm indexes, joining series_metadata for
series-level authors. No external search engine needed.

- Replace search.rs Meilisearch HTTP calls with PostgreSQL queries
- Remove meili.rs from indexer, sync_meili call from job pipeline
- Remove MEILI_URL/MEILI_MASTER_KEY from config, state, env files
- Remove meilisearch service from docker-compose.yml
- Add migration 0027: drop sync_metadata, enable pg_trgm, add indexes
- Remove search resync button/endpoint (no longer needed)
- Update all documentation (CLAUDE.md, README.md, AGENTS.md, PLAN.md)

API contract unchanged — same SearchResponse shape returned.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/backoffice/lib/api.ts

@@ -406,12 +406,6 @@ export async function getThumbnailStats() {
   return apiFetch<ThumbnailStats>("/settings/thumbnail/stats");
 }
 
-export async function forceSearchResync() {
-  return apiFetch<{ success: boolean; message: string }>("/settings/search/resync", {
-    method: "POST",
-  });
-}
-
 export async function convertBook(bookId: string) {
   return apiFetch<IndexJobDto>(`/books/${bookId}/convert`, { method: "POST" });
 }