fix: remove uv.lock from .gitignore to track dependency versions

[wshino]

Summary

• Remove uv.lock from .gitignore to ensure consistent dependency versions across all environments

Rationale

The uv.lock file should be committed to version control as it:

• Ensures reproducible builds across different environments
• Prevents dependency version mismatches between developers
• Follows best practices for modern Python package managers (similar to package-lock.json in npm or Cargo.lock in Rust)

Changes

• Removed uv.lock entry from .gitignore

Test Plan

• Verified .gitignore is updated correctly
• Confirmed no existing uv.lock file is affected
• Future uv.lock files will be properly tracked by Git