feat: Enhance frontend loading experience and service status handling

### Summary of Changes
- Removed proxy configuration in `rsbuild.config.js` as the API Gateway is not running.
- Added smooth transitions and gentle loading overlays in CSS for improved user experience during data loading.
- Updated `Dashboard` component to conditionally display loading spinner and gentle loading overlay based on data fetching state.
- Enhanced `useOfflineAwareServiceStatus` and `useOfflineAwareSystemData` hooks to manage loading states and service status more effectively.
- Increased refresh intervals for service status and system data to reduce API call frequency.

### Expected Results
- Improved user experience with smoother loading transitions and better feedback during data refreshes.
- Enhanced handling of service status checks, providing clearer information when services are unavailable.
- Streamlined code for managing loading states, making it easier to maintain and extend in the future.

frontend/rsbuild.config.js

@@ -15,12 +15,7 @@ export default defineConfig({
   ],
   server: {
     port: 3000,
-    proxy: {
-      '/api': {
-        target: 'http://localhost:8080',
-        changeOrigin: true,
-      },
-    },
+    // Removed proxy since API Gateway is not running
   },
   html: {
     template: './public/index.html',
@@ -36,7 +31,7 @@ export default defineConfig({
     },
     define: {
       'process.env.REACT_APP_API_URL': JSON.stringify(process.env.REACT_APP_API_URL || 'http://localhost:8080'),
-      'process.env.REACT_APP_ADAPTERS_URL': JSON.stringify(process.env.REACT_APP_ADAPTERS_URL || 'http://localhost:8000'),
+      'process.env.REACT_APP_ADAPTERS_URL': JSON.stringify(process.env.REACT_APP_ADAPTERS_URL || 'http://localhost:8001'),
       'process.env.REACT_APP_DOCS_URL': JSON.stringify(process.env.REACT_APP_DOCS_URL || 'http://localhost:8083'),
     },
   },