🔐 refactor: Improve MCP Auth UX for Agent Panel (#9762)

* chore: Improve logging format for initial flow state creation

* refactor: MCP Tool Management with Improved Auth Handling and State Management

- Updated `CustomUserVarsSection` to include optional localization for placeholder text.
- Refactored `MCPToolSelectDialog` to streamline tool addition and management, including improved handling of authentication data.
- Introduced a new `addToolsToForm` function to encapsulate logic for adding tools to the form state.
- Enhanced `useRemoveMCPTool` hook to simplify tool removal logic and ensure proper state updates.
- Added loading state management for custom variable saving to improve user experience.

* refactor: Enhance MCP Tool Removal Logic and Integrate Toast Notifications

- Updated `MCPToolSelectDialog` to utilize the new `removeTool` function from the `useRemoveMCPTool` hook for improved tool removal handling.
- Refactored `useRemoveMCPTool` to accept options for toast notifications, allowing for more flexible user feedback during tool removal.
- Removed the previous inline tool removal logic to streamline the component's code and improve maintainability.

* refactor: Enhance user plugins mutation to invalidate MCP auth values on uninstall

* refactor: Replace refetchQueries with invalidateQueries for improved cache management

* chore: remove unused i18n key

client/src/components/SidePanel/MCP/MCPPanel.tsx

@@ -31,9 +31,9 @@ function MCPPanelContent() {
       showToast({ message: localize('com_nav_mcp_vars_updated'), status: 'success' });
 
       await Promise.all([
-        queryClient.refetchQueries([QueryKeys.mcpTools]),
-        queryClient.refetchQueries([QueryKeys.mcpAuthValues]),
-        queryClient.refetchQueries([QueryKeys.mcpConnectionStatus]),
+        queryClient.invalidateQueries([QueryKeys.mcpTools]),
+        queryClient.invalidateQueries([QueryKeys.mcpAuthValues]),
+        queryClient.invalidateQueries([QueryKeys.mcpConnectionStatus]),
       ]);
     },
     onError: (error: unknown) => {