🔌 refactor: MCP UI with Improved Accessibility and Reusable Components (#11118)

* feat: enhance MCP server selection UI with new components and improved accessibility

* fix(i18n): add missing com_ui_mcp_servers translation key

The MCP server menu aria-label was referencing a non-existent translation
key. Added the missing key for accessibility.

* feat(MCP): enhance MCP components with improved accessibility and focus management

* fix(i18n): remove outdated MCP server translation keys

* fix(MCPServerList): improve color contrast by updating text color for no MCP servers message

* refactor(MCP): Server status components and improve user action handling
Updated MCPServerStatusIcon to use a unified icon system for better clarity
Introduced new MCPCardActions component for standardized action buttons on server cards
Created MCPServerCard component to encapsulate server display logic and actions
Enhanced MCPServerList to render MCPServerCard components, improving code organization
Added MCPStatusBadge for consistent status representation in dialogs
Updated utility functions for status color and text retrieval to align with new design
Improved localization keys for better clarity and consistency in user messages

* style(MCP): update button and card background styles for improved UI consistency

* feat(MCP): implement global server initialization state management using Jotai

* refactor(MCP): modularize MCPServerDialog into structured component architecture

- Split monolithic dialog into dedicated section components (Auth, BasicInfo, Connection, Transport, Trust)
- Extract form logic into useMCPServerForm custom hook
- Add utility modules for JSON import and URL handling
- Introduce reusable SecretInput component in @librechat/client
- Remove deprecated MCPAuth component

* style(MCP): update button styles for improved layout and adjust empty state background color

* refactor(Radio): enhance component mounting logic and background style updates

* refactor(translation): remove unused keys and streamline localization strings

client/src/components/MCP/MCPConfigDialog.tsx

@@ -71,7 +71,14 @@ export default function MCPConfigDialog({
     });
   }, [serverStatus, serverName, localize]);
 
-  // Helper function to render status badge based on connection state
+  /**
+   * Render status badge with unified color system:
+   * - Blue: Connecting/In-progress
+   * - Amber: Needs action (OAuth required)
+   * - Gray: Disconnected (neutral/inactive)
+   * - Green: Connected (success)
+   * - Red: Error
+   */
   const renderStatusBadge = () => {
     if (!serverStatus) {
       return null;
@@ -79,46 +86,51 @@ export default function MCPConfigDialog({
 
     const { connectionState, requiresOAuth } = serverStatus;
 
+    // Connecting: blue (in progress)
     if (connectionState === 'connecting') {
       return (
         <div className="flex items-center gap-2 rounded-full bg-blue-50 px-2 py-0.5 text-xs font-medium text-blue-600 dark:bg-blue-950 dark:text-blue-400">
-          <Spinner className="h-3 w-3" />
+          <Spinner className="size-3" />
           <span>{localize('com_ui_connecting')}</span>
         </div>
       );
     }
 
+    // Disconnected: check if needs action
     if (connectionState === 'disconnected') {
       if (requiresOAuth) {
+        // Needs OAuth: amber (requires action)
         return (
           <div className="flex items-center gap-2 rounded-full bg-amber-50 px-2 py-0.5 text-xs font-medium text-amber-600 dark:bg-amber-950 dark:text-amber-400">
-            <KeyRound className="h-3 w-3" aria-hidden="true" />
-            <span>{localize('com_ui_oauth')}</span>
-          </div>
-        );
-      } else {
-        return (
-          <div className="flex items-center gap-2 rounded-full bg-orange-50 px-2 py-0.5 text-xs font-medium text-orange-600 dark:bg-orange-950 dark:text-orange-400">
-            <PlugZap className="h-3 w-3" aria-hidden="true" />
-            <span>{localize('com_ui_offline')}</span>
+            <KeyRound className="size-3" aria-hidden="true" />
+            <span>{localize('com_nav_mcp_status_needs_auth')}</span>
           </div>
         );
       }
+      // Simply disconnected: gray (neutral)
+      return (
+        <div className="flex items-center gap-2 rounded-full bg-gray-100 px-2 py-0.5 text-xs font-medium text-gray-600 dark:bg-gray-800 dark:text-gray-400">
+          <PlugZap className="size-3" aria-hidden="true" />
+          <span>{localize('com_nav_mcp_status_disconnected')}</span>
+        </div>
+      );
     }
 
+    // Error: red
     if (connectionState === 'error') {
       return (
         <div className="flex items-center gap-2 rounded-full bg-red-50 px-2 py-0.5 text-xs font-medium text-red-600 dark:bg-red-950 dark:text-red-400">
-          <AlertTriangle className="h-3 w-3" aria-hidden="true" />
+          <AlertTriangle className="size-3" aria-hidden="true" />
           <span>{localize('com_ui_error')}</span>
         </div>
       );
     }
 
+    // Connected: green
     if (connectionState === 'connected') {
       return (
-        <div className="flex items-center gap-2 rounded-full bg-green-100 px-2 py-0.5 text-xs font-medium text-green-700 dark:bg-green-900 dark:text-green-300">
-          <div className="h-1.5 w-1.5 rounded-full bg-green-500" />
+        <div className="flex items-center gap-2 rounded-full bg-green-50 px-2 py-0.5 text-xs font-medium text-green-600 dark:bg-green-950 dark:text-green-400">
+          <div className="size-1.5 rounded-full bg-green-500" />
           <span>{localize('com_ui_active')}</span>
         </div>
       );