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

dashboard/src/communication/mod.rs

@@ -36,6 +36,8 @@ pub enum ServiceAction {
     Start,
     Stop,
     Status,
+    UserStart,  // User-initiated start (clears user-stopped flag)
+    UserStop,   // User-initiated stop (marks as user-stopped)
 }
 
 /// ZMQ consumer for receiving metrics from agents