chore: align CI workflow with current execution model and contributor…

[mxj711]

Summary

• refactor the CI workflow from 3 coarse jobs into 5 focused jobs: ruff-lint, ruff-format, mypy, pyright, and test
• align CI setup with current repo conventions by using newer GitHub Actions versions, uv run, uv sync --only-group dev for Ruff-only jobs, and uv sync --extra motrix for the test job
• tighten workflow behavior with explicit concurrency, read-only permissions, persist-credentials: false, and coverage output appended to $GITHUB_STEP_SUMMARY
• update CONTRIBUTING.md and localized contributing docs so the documented CI workflow matches the actual pipeline

Linked Work

• Issue: fill in the CI/workflow issue you created
• Milestone: fill if applicable

Validation

• make check
• uv run pytest -m "not slow"
• Additional task-specific validation listed below

Commands actually run:

  git diff --stat
  git diff -- .github/workflows/ci.yml CONTRIBUTING.md docs/zh_CN/CONTRIBUTING.md docs/ja/CONTRIBUTING.md docs/ko/CONTRIBUTING.md
  sed -n '1,240p' .github/pull_request_template.md

Impact

• Backend impact: none
• Platform impact: both
• Training effect expected: no

Artifacts

• W&B:
• benchmark result:
• video / screenshot:
• ONNX / checkpoint:

Checklist

• Added or updated tests where needed
• Updated docs if behavior or workflow changed
• Linked the driving issue
• Noted any follow-up work explicitly