v0.60.0: Faster search, Missions model selector, and Missions validation overhaul

New features

- Missions model selector - Choose specific models for Missions workers
- Prevent idle sleep - CLI now prevents system idle sleep during Missions execution

Improvements

- Faster search - Sped up search functionality in large repositories with fuzzy search support

Bug fixes

- Missions validation overhaul - Complete overhaul of Missions validation for improved reliability
- Missions worker timeouts - Improved Missions worker timeout handling
- Subagent model inheritance - Fixed model inheritance for subagents
- Diff word highlights - Fixed incorrect line wrapping in diff word-level highlights
- Gemini tool usage - Improved Gemini tool usage reliability
- Readiness report sanitization - Improved sanitization of sensitive data in readiness reports
- TUI daemon shutdown - Fixed stopping TUI-spawned daemon on shutdown