Deploy and run behind a strict firewall

Stations on locked-down networks could not reach the third-party hosts used to download the Python runtime and to transfer deployment archives, so setup failed where IT could not allowlist them.

• Added a TofuPilot-hosted mirror for Python interpreter downloads, so station networks now only need *.tofupilot.app, tofupilot.sh and dl.tofupilot.sh (plus PyPI).
• Moved deployment uploads and downloads to artifacts.tofupilot.app, with no change to how stations work — they follow whatever address the API returns.
• Added a clear error when a project's sources exceed the 95 MB upload limit, instead of an opaque failure part-way through.
• Added overrides for air-gapped setups: point the mirror at your own host, or turn it off to use the upstream source.