feat: enable Watchtower HTTP API and use internal registry

- Add HTTP API to Watchtower for CI/CD triggered updates
- Update custom container images to use git.schweitz.internal
- Add GITEA_TOKEN env var to scheduler for release cleanup task

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

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

stacks/tatlock.yml

@@ -4,11 +4,11 @@ version: '3.8'
 # Purpose: OpenAI-compatible API server with LLM agent orchestration
 # Port: 8000 (API)
 # Network: docker-dataplane
-# Image: tower-of-joy:3002/jpmschweitzer/tatlock (internal registry)
+# Image: git.schweitz.internal/jpmschweitzer/tatlock (internal registry)
 
 services:
   tatlock:
-    image: tower-of-joy:3002/jpmschweitzer/tatlock:latest
+    image: git.schweitz.internal/jpmschweitzer/tatlock:latest
     container_name: tatlock
     restart: unless-stopped