Fix: remove :ro from SSH key volume mount

The container needs write access to chmod 600 the key file.

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

.github/workflows/update.yml

@@ -111,8 +111,8 @@ jobs:
 
           docker run --rm \
             --user root \
-            -v "$SSH_DIR/deploy_key":/root/.ssh/deploy_key:ro \
-            -v "$SSH_DIR/known_hosts":/root/.ssh/known_hosts:ro \
+            -v "$SSH_DIR/deploy_key":/root/.ssh/deploy_key \
+            -v "$SSH_DIR/known_hosts":/root/.ssh/known_hosts \
             -e DOCKER_REGISTRY \
             -e DOCKER_REGISTRY_TOKEN \
             "$SFP_IMAGE" \