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/api/src/state.rs

@@ -12,8 +12,6 @@ use tokio::sync::{Mutex, RwLock, Semaphore};
 pub struct AppState {
     pub pool: sqlx::PgPool,
     pub bootstrap_token: Arc<str>,
-    pub meili_url: Arc<str>,
-    pub meili_master_key: Arc<str>,
     pub page_cache: Arc<Mutex<LruCache<String, Arc<Vec<u8>>>>>,
     pub page_render_limit: Arc<Semaphore>,
     pub metrics: Arc<Metrics>,