Add stack-type labels and public service stacks

Add com.ghost.tel/stack-type labels to all stacks:
- prod (17): Production services from core
- dev-only (11): Experimental/device-specific services
- public (8): Public-facing services (uplink.tel, sequela.tel)

New public stacks from docker-public:
- nitter-public: Nitter instance for uplink.tel
- freshrss-public: FreshRSS for uplink.tel
- rsshub-public: RSSHub for uplink.tel
- searx-public: SearXNG for uplink.tel
- wikijs-public: Wiki.js for sequela.tel
- matomo-public: Matomo analytics for sequela.tel

Also fixes:
- Remove obsolete 'version' key from compose files
- Fix snowflake to remove duplicate watchtower service
- Standardize compose file formatting

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

stacks/syncthing/docker-compose.yml

@@ -19,6 +19,7 @@ services:
     networks:
       - web
     labels:
+      - "com.ghost.tel/stack-type=dev-only"
       - "traefik.enable=true"
       - "traefik.http.routers.syncthing.entrypoints=https"
       - "traefik.http.routers.syncthing.rule=Host(`syncthing.${DOMAIN}`)"