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/scheduler.yml

@@ -4,11 +4,11 @@ version: '3.8'
 # Purpose: System-wide maintenance orchestration - backups, doc mirroring, cleanup, task automation
 # Port: 8090 (API + UI)
 # Network: docker-dataplane
-# Image: tower-of-joy:3002/jpmschweitzer/scheduler (internal registry)
+# Image: git.schweitz.internal/jpmschweitzer/scheduler (internal registry)
 
 services:
   scheduler:
-    image: tower-of-joy:3002/jpmschweitzer/scheduler:latest
+    image: git.schweitz.internal/jpmschweitzer/scheduler:latest
     container_name: scheduler
     restart: unless-stopped
 
@@ -35,6 +35,7 @@ services:
       - GITEA_PASSWORD=${GITEA_LIBRARY_PASSWORD}
       - GITEA_SSH_HOST=gitea
       - GITEA_SSH_PORT=22
+      - GITEA_TOKEN=${GITEA_TOKEN}
       - BACKUP_RETENTION_DAILY=7
       - BACKUP_RETENTION_WEEKLY=4
       - BACKUP_RETENTION_MONTHLY=12