ci: skip uv lock generation on forks

[chtruong814]

What does this PR do ?

Skip the uv lock generation workflow for forked pull requests while allowing same-repository PRs in the canonical repository to keep updating lock files.

Changelog

• Add a job-level guard to the uv lock generation workflow.
• Require the PR head repository to match the workflow repository before running PAT-backed checkout and push steps.

Before your PR is "Ready for review"

Pre checks:

• Make sure you read and followed Contributor guidelines
• Did you write any new necessary tests? Workflow-only change; no tests added.
• Did you add or update any necessary documentation? Not needed for this CI-only change.

Additional Information

• Related to #