refactor(ai): remove crawl4ai service, add backrest config to repo

- Remove crawl4ai service from ai/compose.yaml (will use local MCP instead)
- Remove crawl4ai backup volume from core/compose.yaml
- Add core/backrest/config.json (infrastructure as code)
- Change backrest from volume to bind-mounted config
- Update CLAUDE.md and README.md documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

ai/compose.yaml

@@ -146,25 +146,6 @@ services:
       # Watchtower
       - 'com.centurylinklabs.watchtower.enable=${WATCHTOWER_LABEL_ENABLE}'
 
-  # Crawl4AI - Web scraping for LLMs (internal API, no public access)
-  crawl4ai:
-    image: ${AI_CRAWL4AI_IMAGE:-unclecode/crawl4ai:latest}
-    container_name: ${AI_COMPOSE_PROJECT_NAME}_crawl4ai
-    restart: unless-stopped
-    environment:
-      TZ: ${TIMEZONE:-Europe/Berlin}
-      # API configuration
-      PORT: ${AI_CRAWL4AI_PORT:-11235}
-    volumes:
-      - ai_crawl4ai_data:/app/.crawl4ai
-    networks:
-      - compose_network
-    labels:
-      # No Traefik exposure - internal only
-      - 'traefik.enable=false'
-      # Watchtower
-      - 'com.centurylinklabs.watchtower.enable=${WATCHTOWER_LABEL_ENABLE}'
-
   # Facefusion - AI face swapping and enhancement
   facefusion:
     build:
@@ -273,7 +254,5 @@ volumes:
     name: ${AI_COMPOSE_PROJECT_NAME}_postgres_data
   ai_webui_data:
     name: ${AI_COMPOSE_PROJECT_NAME}_webui_data
-  ai_crawl4ai_data:
-    name: ${AI_COMPOSE_PROJECT_NAME}_crawl4ai_data
   ai_facefusion_data:
     name: ${AI_COMPOSE_PROJECT_NAME}_facefusion_data