macOS sidecar: `uv run` re-resolves dependencies using CUDA sources even after `uv sync --no-sources`. Use UV_NO_SOURCES=1 env var instead so it applies to all uv commands in the step. Blank window: When the Tauri app starts without the Python backend running, it showed a completely blank window. Now shows a "Connecting to backend..." spinner, or an error state with instructions to start the backend manually. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>