Fix rebuild indicator with proper timeout and completion detection

- Add automatic timeout mechanism (5 minutes for rebuilds, 30 seconds for services)
- Implement agent hash change detection for rebuild completion
- Add visual feedback states: blue ↻ (in progress), green ✓ (success), red ✗ (failed)
- Clear status automatically after timeout or completion
- Fix command status lifecycle management

dashboard/src/ui/widgets/system.rs

@@ -128,6 +128,11 @@ impl SystemWidget {
         }
     }
 
+    /// Get the current agent hash for rebuild completion detection
+    pub fn get_agent_hash(&self) -> Option<&String> {
+        self.agent_hash.as_ref()
+    }
+
     /// Get mount point for a pool name
     fn get_mount_point_for_pool(&self, pool_name: &str) -> String {
         match pool_name {