refactor: sanitize GITEA_REGISTRY_VAR input by stripping protocol and path

.gitea/workflows/docker-build-push.yml

@@ -71,7 +71,8 @@ jobs:
 
           # Prefer explicit var GITEA_REGISTRY; else, use the same host as server URL
           if [ -n "${GITEA_REGISTRY_VAR:-}" ]; then
-            REGISTRY="$GITEA_REGISTRY_VAR"
+            # Strip protocol and any path if mistakenly provided
+            REGISTRY=$(echo "$GITEA_REGISTRY_VAR" | sed -E 's#^https?://##; s#/.*$##; s#/$##')
           else
             # GITHUB_SERVER_URL like https://gitea.example.com
             REGISTRY=$(echo "$GITHUB_SERVER_URL" | sed -E 's#^https?://##; s#/$##')