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/app/api/settings/search/resync/route.ts

@@ -1,11 +0,0 @@
-import { NextResponse } from "next/server";
-import { forceSearchResync } from "@/lib/api";
-
-export async function POST() {
-  try {
-    const data = await forceSearchResync();
-    return NextResponse.json(data);
-  } catch (error) {
-    return NextResponse.json({ error: "Failed to trigger search resync" }, { status: 500 });
-  }
-}