Add GitHub Actions workflow to run Jetpack Compose performance skill

[riggaroo]

Summary

Adds a new GitHub Actions workflow (.github/workflows/compose_performance_skill.yml) to run the Jetpack Compose performance skill on Kotlin files in android/compose-samples using the Android CLI (android skills add) and google-github-actions/run-gemini-cli.

Details

• Triggers:
  • pull_request when any **/*.kt file (or .github/workflows/compose_performance_skill.yml) is modified.
  • workflow_dispatch with an optional pr_number input (audits the PR's changed .kt files when provided, or audits all **/*.kt files across the repository when omitted).
• Workflow Steps:
  1. Checks out android/compose-samples with full history (fetch-depth: 0).
  2. Installs the Android CLI and runs android skills add --agent=gemini --project=. jetpack-compose-performance to install the skill into .agents/skills/jetpack-compose-performance.
  3. Collects the target .kt files into .gemini/target_files.txt.
  4. Invokes google-github-actions/run-gemini-cli (v0.1.22) using secrets.GEMINI_API_KEY to audit the target Kotlin files against the skill and its references/**/*.md files.
  5. Posts the structured Markdown review findings as a comment on the pull request (and outputs them to the GitHub Actions job summary).
• Updates .gitignore to ignore .gemini/ and .agents/ directories.