moon setup fails: No pre-built available for Python 3.13.12 and no --build flag exposed

[rayhunts]

Describe the bug
Moon setup fails when installing Python ~3.13 because it resolves to version 3.13.12 which has no pre-built binary available from python-build-standalone.

To Reproduce
Steps to reproduce the behavior:

1. Use moon with Python version set to '3.13' in .moon/toolchain.yml
2. Run moon setup
3. See error: No pre-built available for version 3.13.12

Expected behavior
Moon should either:

• Install the latest available pre-built version automatically, OR
• Provide a --build flag to build from source as suggested in the error message

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Fedora Linux 43 (Workstation Edition) x86_64
• Kernel: Linux 6.18.7-200.fc43.x86_64
• Moon version: 1.41.8

Additional context
The error message suggests using --build but moon setup doesn't expose this flag from proto. Would be helpful to either pass through proto flags or handle the resolution more gracefully.
Note: If Python 3.13.0 (or another 3.13.x version) is already installed in the moon cache, this issue will not appear. I verified this by reverting my changes back to version '3.13' - the setup completed without errors because the toolchain was already cached. The error only occurs when moon needs to download and install a new Python version that lacks a pre-built binary.

CC : @ameliarahman