feat: add skill_invocation power-steering check (from closed #2916)

[rysweet]

Summary

Extracts the skill_invocation check from closed PR #2916 (which was closed due to merge conflicts with the package refactor, not because the work was bad).

This check detects when a user requests a skill via slash command (e.g. /pm-architect) but the agent bypasses it and responds directly without invoking the Skill tool.

Changes

• checks_workflow.py: Add _check_skill_invocation() method with try/except fail-open
• considerations.yaml: Add skill_invocation blocker for DEVELOPMENT, INVESTIGATION, MAINTENANCE sessions
• 12 outside-in e2e tests covering Claude, Copilot, and edge cases

How it works

1. Scans transcript for <command-name> tags (injected when user runs a slash command)
2. If found, checks if the Skill tool was called with that skill name
3. If no command-name tag → auto-pass (check not applicable)
4. If skill requested but not invoked → fail (blocker)

Related to #2914

Test plan

• 12 outside-in tests pass (Claude + Copilot sessions)
• 70 existing PS tests still pass
• CI checks pass

Generated with Claude Code

[github-actions]

🤖 Auto-fixed version bump

The version in pyproject.toml has been automatically bumped to the next patch version.

If you need a minor or major version bump instead, please update pyproject.toml manually and push the change.