1. Remove Docker build from create_instance for manifest types — the build
was blocking the HTTP request for several minutes, causing frontend
timeouts and retries. Image is now built lazily on start (via the
existing _prepare_manifest_instance path in start_instance).
2. Increase MAX_CONNECTIONS_PER_USER from 5 to 20 for SSE endpoint —
aggressive reconnect loops from the frontend were exhausting the limit
and causing 429 errors unrelated to tool starting.
Quality gates: ruff clean, tsc --noEmit clean, pytest workspaces (9 passed)
alex
56dd7d3fd3