fix: clear stale Dokku deploy lock before pushing

cancel-in-progress kills the CI job mid-deploy but Dokku's server-side
lock persists, causing subsequent deploys to hang indefinitely.

.forgejo/workflows/build.yaml

@@ -33,6 +33,8 @@ jobs:
           echo "$SSH_PRIVATE_KEY" > ~/.ssh/id_ed25519
           chmod 600 ~/.ssh/id_ed25519
           ssh-keyscan -H 204.110.191.231 >> ~/.ssh/known_hosts
+          # Clear stale deploy lock from cancelled runs
+          ssh dokku@204.110.191.231 apps:unlock towerops || true
           git remote add dokku dokku@204.110.191.231:towerops || true
           git push dokku main:main --force