feat: implement resumable Claude sessions with background execution (#93)

This comprehensive update adds support for resumable Claude Code sessions that can run in the background and be resumed later. Key improvements include:

Backend enhancements:
- Enhanced ProcessRegistry to track both agent runs and Claude sessions
- Added new Tauri commands: list_running_claude_sessions, get_claude_session_output
- Improved Claude process management with proper session ID extraction and lifecycle handling
- Enhanced cancellation logic with registry-based process killing and fallback mechanisms
- Added live output capture and storage for session persistence

Frontend improvements:
- New RunningClaudeSessions component to display and manage active sessions
- Added streaming state management and session tracking in App component
- Implemented navigation protection when Claude is actively streaming
- Enhanced ClaudeCodeSession component with streaming callbacks and session management

Configuration updates:
- Updated .gitignore to exclude documentation files (AGENTS.md, CLAUDE.md, *_TASK.md)

This feature enables users to start Claude sessions, navigate away while Claude continues processing, and resume sessions later from the Projects view, significantly improving the user experience for long-running AI interactions.

.gitignore

@@ -24,4 +24,7 @@ dist-ssr
 *.sw?
 temp_lib/
 
-.cursor/
+.cursor/
+AGENTS.md
+CLAUDE.md
+*_TASK.md