Fix storage display and improve UI formatting

- Fix duplicate storage pool issue by clearing cache on agent startup
- Change storage pool header text to normal color for better readability
- Improve services panel tree icons with proper └─ symbols for last items
- Ensure fresh metrics data on each agent restart

agent/src/cache/mod.rs

@@ -19,8 +19,8 @@ impl SimpleCache {
             persist_path: config.persist_path,
         };
         
-        // Load from disk on startup
-        cache.load_from_disk();
+        // Clear cache file on startup to ensure fresh data
+        cache.clear_cache_file();
         cache
     }
 
@@ -82,6 +82,16 @@ impl SimpleCache {
             }
         }
     }
+
+    /// Clear cache file on startup to ensure fresh data
+    fn clear_cache_file(&self) {
+        if Path::new(&self.persist_path).exists() {
+            match fs::remove_file(&self.persist_path) {
+                Ok(_) => info!("Cleared cache file {} on startup", self.persist_path),
+                Err(e) => warn!("Failed to clear cache file {}: {}", self.persist_path, e),
+            }
+        }
+    }
 }