Auto-resolve modal dependency overlay conflicts

[chriscarrollsmith]

Summary

• Adds a modal-only conflict resolver to the propagate workflow for pyproject.toml and uv.lock conflicts.
• Preserves the Modal branch dependency overlay, regenerates uv.lock, and pushes the merge when only those known files conflict.
• Keeps the fallback PR path for all other conflicts.

Test plan

• Simulated the current origin/main into origin/modal merge locally.
• Verified the resolver clears pyproject.toml and uv.lock conflicts.
• Verified the resolved pyproject.toml keeps modal>=0.73.162 and uv.lock still contains the modal package.

Made with Cursor