fix: brain service — pgvector extension init, meili key length

Brain service fully operational:
- All 6 containers running
- API responds on /api/health
- Worker processes items (fetch, screenshot, classify, index)
- Tested: link creation, background processing, asset archival

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

services/brain/app/main.py

@@ -27,11 +27,13 @@ app.include_router(router)
 
 @app.on_event("startup")
 async def startup():
+    from sqlalchemy import text as sa_text
     from app.database import engine, Base
     from app.models.item import Item, ItemAsset, AppLink  # noqa: import to register models
 
-    # Create tables if they don't exist
+    # Enable pgvector extension before creating tables
     async with engine.begin() as conn:
+        await conn.execute(sa_text("CREATE EXTENSION IF NOT EXISTS vector"))
         await conn.run_sync(Base.metadata.create_all)
 
     # Ensure Meilisearch index exists

services/brain/docker-compose.yml

@@ -12,7 +12,7 @@ services:
       - DATABASE_URL=postgresql+asyncpg://brain:brain@brain-db:5432/brain
       - REDIS_URL=redis://brain-redis:6379/0
       - MEILI_URL=http://brain-meili:7700
-      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-key}
+      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-secure-key-2026}
       - BROWSERLESS_URL=http://brain-browserless:3000
       - OPENAI_API_KEY=${OPENAI_API_KEY}
       - OPENAI_MODEL=${OPENAI_MODEL:-gpt-4o-mini}
@@ -43,7 +43,7 @@ services:
       - DATABASE_URL=postgresql+asyncpg://brain:brain@brain-db:5432/brain
       - REDIS_URL=redis://brain-redis:6379/0
       - MEILI_URL=http://brain-meili:7700
-      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-key}
+      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-secure-key-2026}
       - BROWSERLESS_URL=http://brain-browserless:3000
       - OPENAI_API_KEY=${OPENAI_API_KEY}
       - OPENAI_MODEL=${OPENAI_MODEL:-gpt-4o-mini}
@@ -85,7 +85,7 @@ services:
     container_name: brain-meili
     restart: unless-stopped
     environment:
-      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-key}
+      - MEILI_MASTER_KEY=${MEILI_MASTER_KEY:-brain-meili-secure-key-2026}
       - MEILI_ENV=production
     volumes:
       - ./data/meili:/meili_data