Migrate from SQLite to PostgreSQL

- Replace modernc.org/sqlite with jackc/pgx/v5
- Update all SQL queries for PostgreSQL syntax ($1, $2 placeholders)
- Use snake_case column names throughout
- Replace SQLite FTS5 with PostgreSQL tsvector/tsquery full-text search
- Add connection pooling with pgxpool
- Support Docker secrets for database password
- Add trigger to normalize feed URLs (strip https://, http://, www.)
- Fix anchor feed detection regex to avoid false positives
- Connect app container to atproto network for PostgreSQL access
- Add version indicator to dashboard UI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -6,11 +6,19 @@ services:
     stop_grace_period: 30s
     env_file:
       - pds.env
+    environment:
+      DB_HOST: atproto-postgres
+      DB_PORT: 5432
+      DB_USER: news_1440
+      DB_PASSWORD_FILE: /run/secrets/db_password
+      DB_NAME: news_1440
+    secrets:
+      - db_password
     volumes:
-      - ./feeds:/app/feeds
       - ./vertices.txt.gz:/app/vertices.txt.gz:ro
     networks:
       - proxy
+      - atproto
     labels:
       - "traefik.enable=true"
       # Production: HTTPS with Let's Encrypt
@@ -29,6 +37,12 @@ services:
       # Shared service
       - "traefik.http.services.app-1440-news.loadbalancer.server.port=4321"
 
+secrets:
+  db_password:
+    file: ../postgres/secrets/news_1440_password.txt
+
 networks:
   proxy:
     external: true
+  atproto:
+    external: true