[purp]

Summary

Fix Python CI typechecking of standalone scripts that import sibling modules. Add tasks/scripts to ty's search path in the shared python:typecheck task so local and CI runs use the same module resolution.

Related Issue

No issue: build-fix exception for an author with verified repository write access. The first Branch Checks attempt on #5260 failed on both Linux architectures because check_review_readiness.py could not resolve check_maintainer_approval or label_accepted_work.

Changes

• Add --extra-search-path tasks/scripts to the existing ty invocation; keep all diagnostics enabled.

Release Notes

Testing

• mise run python:typecheck passes across the configured Python paths, including its protobuf-generation dependency.
• Reproduced both unresolved-import errors against feat(review): automatically label new PRs for accepted work #5260's scripts without the flag; the same scripts and tests typecheck successfully with the flag.
• mise run validate and git diff --check pass.
• Checks appropriate to the affected code and behavior pass
• Unit tests added/updated (configuration-only fix; verified with the actual typechecker)
• E2E tests added/updated (not applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable)