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>

docker-compose.yml

@@ -15,20 +15,6 @@ services:
       timeout: 5s
       retries: 5
 
-  meilisearch:
-    image: getmeili/meilisearch:v1.12
-    env_file:
-      - .env
-    ports:
-      - "7700:7700"
-    volumes:
-      - meili_data:/meili_data
-    healthcheck:
-      test: ["CMD", "wget", "-q", "-O", "-", "http://127.0.0.1:7700/health"]
-      interval: 10s
-      timeout: 5s
-      retries: 5
-
   api:
     build:
       context: .
@@ -43,8 +29,6 @@ services:
     depends_on:
       postgres:
         condition: service_healthy
-      meilisearch:
-        condition: service_healthy
     healthcheck:
       test: ["CMD", "wget", "-q", "-O", "-", "http://127.0.0.1:7080/health"]
       interval: 10s
@@ -68,8 +52,6 @@ services:
         condition: service_healthy
       postgres:
         condition: service_healthy
-      meilisearch:
-        condition: service_healthy
     healthcheck:
       test: ["CMD", "wget", "-q", "-O", "-", "http://127.0.0.1:7081/health"]
       interval: 10s
@@ -98,4 +80,3 @@ services:
 
 volumes:
   postgres_data:
-  meili_data: