fix(cd): reopen controlled push deploy lane

.gitea/workflows/cd.yaml

@@ -11,7 +11,11 @@ name: CD Pipeline
 
 on:
   # 2026-06-28 Codex: 110 host runner/CD lane pressure incident.
-  # Production CD is manual-only until the runner is moved or rate-limited.
+  # Production CD is reopened for controlled apply through the dedicated
+  # capacity=1 cd-lane drain verifier; the host pressure gate below remains
+  # fail-closed before build starts.
+  push:
+    branches: [main]
   workflow_dispatch:
     # 手動觸發永遠可用（用於補跑、緊急部署）