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/indexer/src/lib.rs

@@ -3,7 +3,6 @@ pub mod api;
 pub mod batch;
 pub mod converter;
 pub mod job;
-pub mod meili;
 pub mod scheduler;
 pub mod scanner;
 pub mod utils;
@@ -15,6 +14,4 @@ use sqlx::PgPool;
 #[derive(Clone)]
 pub struct AppState {
     pub pool: PgPool,
-    pub meili_url: String,
-    pub meili_master_key: String,
 }