⚒️ fix: MCP Initialization Flows (#8734)

* fix: add OAuth flow back in to success state

* feat: disable server clicks during initialization to prevent spam

* fix: correct new tab behavior for OAuth between one-click and normal initialization flows

* fix: stop polling on error during oauth (was infinite popping toasts because we didn't clear interval)

* fix: cleanupServerState should be called after successful cancelOauth, not before

* fix: change from completeFlow to failFlow to avoid stale client IDs on OAuth after cancellation

* fix: add logic to differentiate between cancelled and failed flows when checking status for indicators (so error triangle indicator doesn't show up on cancellaiton)

client/src/components/Chat/Input/MCPSelect.tsx

@@ -13,6 +13,7 @@ function MCPSelect() {
     batchToggleServers,
     getServerStatusIconProps,
     getConfigDialogProps,
+    isInitializing,
     localize,
   } = useMCPServerManager();
 
@@ -32,14 +33,18 @@ function MCPSelect() {
   const renderItemContent = useCallback(
     (serverName: string, defaultContent: React.ReactNode) => {
       const statusIconProps = getServerStatusIconProps(serverName);
+      const isServerInitializing = isInitializing(serverName);
 
       // Common wrapper for the main content (check mark + text)
       // Ensures Check & Text are adjacent and the group takes available space.
       const mainContentWrapper = (
         <button
           type="button"
-          className="flex flex-grow items-center rounded bg-transparent p-0 text-left transition-colors focus:outline-none"
+          className={`flex flex-grow items-center rounded bg-transparent p-0 text-left transition-colors focus:outline-none ${
+            isServerInitializing ? 'opacity-50' : ''
+          }`}
           tabIndex={0}
+          disabled={isServerInitializing}
         >
           {defaultContent}
         </button>
@@ -58,7 +63,7 @@ function MCPSelect() {
 
       return mainContentWrapper;
     },
-    [getServerStatusIconProps],
+    [getServerStatusIconProps, isInitializing],
   );
 
   // Don't render if no servers are selected and not pinned