Fix physical drive grouping logic for unified pool visualization

Updated filesystem grouping to use extract_base_device method for proper
partition-to-drive mapping. This ensures nvme0n1p1 and nvme0n1p2 are
correctly grouped under nvme0n1 drive pool instead of separate pools.

agent/src/collectors/disk.rs

@@ -419,13 +419,22 @@ impl DiskCollector {
             // Get the physical drive name for this mount point
             if let Some(devices) = self.detected_devices.get(&fs.mount_point) {
                 if let Some(device_name) = devices.first() {
-                    // Extract drive name (e.g., "nvme0n1" from "nvme0n1")
-                    let drive_name = device_name.clone();
+                    // Extract base drive name from detected device
+                    let drive_name = Self::extract_base_device(device_name)
+                        .unwrap_or_else(|| device_name.clone());
+                    
+                    debug!("Grouping filesystem {} (device: {}) under drive: {}", 
+                           fs.mount_point, device_name, drive_name);
+                    
                     grouped.entry(drive_name).or_insert_with(Vec::new).push(fs.clone());
                 }
             }
         }
         
+        debug!("Filesystem grouping result: {} drives with filesystems: {:?}", 
+               grouped.len(), 
+               grouped.keys().collect::<Vec<_>>());
+        
         Ok(grouped)
     }