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>

.env.example

@@ -9,9 +9,6 @@
 # REQUIRED - Change these values in production!
 # =============================================================================
 
-# Master key for Meilisearch authentication (required)
-MEILI_MASTER_KEY=change-me-in-production
-
 # Bootstrap token for initial API admin access (required)
 # Use this token for the first API calls before creating proper API tokens
 API_BOOTSTRAP_TOKEN=change-me-in-production
@@ -28,9 +25,6 @@ API_BASE_URL=http://api:7080
 INDEXER_LISTEN_ADDR=0.0.0.0:7081
 INDEXER_SCAN_INTERVAL_SECONDS=5
 
-# Meilisearch Search Engine
-MEILI_URL=http://meilisearch:7700
-
 # PostgreSQL Database
 DATABASE_URL=postgres://stripstream:stripstream@postgres:5432/stripstream
 
@@ -77,5 +71,4 @@ THUMBNAILS_HOST_PATH=./data/thumbnails
 # - API: change "7080:7080" to "YOUR_PORT:7080"
 # - Indexer: change "7081:7081" to "YOUR_PORT:7081"
 # - Backoffice: change "7082:7082" to "YOUR_PORT:7082"
-# - Meilisearch: change "7700:7700" to "YOUR_PORT:7700"
 # - PostgreSQL: change "6432:5432" to "YOUR_PORT:5432"