perf: make .uv-cache as shared folder

[fatelei]

Description

fix #703

Type of Change

• Bug fix
• New feature
• Refactor
• Performance improvement
• Other

Essential Checklist

Testing

• I have tested the changes locally and confirmed they work as expected
• I have added unit tests where necessary and they pass successfully

Bug Fix (if applicable)

• I have used GitHub syntax to close the related issue (e.g., Fixes #123 or Closes #123)

Additional Information

Please provide any additional context that would help reviewers understand the changes.

[gemini-code-assist]

Code Review

This pull request updates the logic for determining the uv cache directory, allowing for a configurable path or a shared directory under the plugin working path. Feedback identifies a missing field in the configuration struct that will cause a compilation error and suggests converting the cache path to an absolute path to ensure correct resolution during command execution.