pi-guardrails v0.10.0

6356335: Add command-based onboarding for new users.
- add /guardrails:onboarding command and session-start hint when setup is pending
- replace auto-open onboarding with explicit overlay flow
- add onboarding completion marker for config compatibility and first-run state
- improve onboarding wizard copy and defaults/recap UX

828c019: Fix dangerous command confirmation UI scrolling for long multi-line commands.
97597c2: Fix home-directory default policy rules so ~-based patterns match correctly and expand to the current user’s home directory during blocking and existence checks.