Add scheduled auto-deploy at 3h, 13h, 19h, 23h daily

Also rotates SECRET_ANALYTICS at each deploy for dynamic endpoint.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -2,6 +2,8 @@ name: Deploy to production
 
 on:
   workflow_dispatch:
+  schedule:
+    - cron: '0 3,13,19,23 * * *'
 
 jobs:
   deploy: