Implement user-stopped service tracking system

Add comprehensive tracking for services stopped via dashboard to prevent
false alerts when users intentionally stop services.

Features:
- User-stopped services report Status::Ok instead of Warning
- Persistent storage survives agent restarts
- Dashboard sends UserStart/UserStop commands
- Agent tracks and syncs user-stopped state globally
- Systemd collector respects user-stopped flags

Implementation:
- New service_tracker module with persistent JSON storage
- Enhanced ServiceAction enum with UserStart/UserStop variants
- Global singleton tracker accessible by collectors
- Service status logic updated to check user-stopped flag
- Dashboard version now uses CARGO_PKG_VERSION automatically

Bump version to v0.1.43

agent/src/main.rs

@@ -9,6 +9,7 @@ mod communication;
 mod config;
 mod metrics;
 mod notifications;
+mod service_tracker;
 mod status;
 
 use agent::Agent;