🛡️ fix: Secure MCP/Actions OAuth Flows, Resolve Race Condition & Tool Cache Cleanup (#11756)

* 🔧 fix: Update OAuth error message for clarity

- Changed the default error message in the OAuth error route from 'Unknown error' to 'Unknown OAuth error' to provide clearer context during authentication failures.

* 🔒 feat: Enhance OAuth flow with CSRF protection and session management

- Implemented CSRF protection for OAuth flows by introducing `generateOAuthCsrfToken`, `setOAuthCsrfCookie`, and `validateOAuthCsrf` functions.
- Added session management for OAuth with `setOAuthSession` and `validateOAuthSession` middleware.
- Updated routes to bind CSRF tokens for MCP and action OAuth flows, ensuring secure authentication.
- Enhanced tests to validate CSRF handling and session management in OAuth processes.

* 🔧 refactor: Invalidate cached tools after user plugin disconnection

- Added a call to `invalidateCachedTools` in the `updateUserPluginsController` to ensure that cached tools are refreshed when a user disconnects from an MCP server after a plugin authentication update. This change improves the accuracy of tool data for users.

* chore: imports order

* fix: domain separator regex usage in ToolService

- Moved the declaration of `domainSeparatorRegex` to avoid redundancy in the `loadActionToolsForExecution` function, improving code clarity and performance.

* chore: OAuth flow error handling and CSRF token generation

- Enhanced the OAuth callback route to validate the flow ID format, ensuring proper error handling for invalid states.
- Updated the CSRF token generation function to require a JWT secret, throwing an error if not provided, which improves security and clarity in token generation.
- Adjusted tests to reflect changes in flow ID handling and ensure robust validation across various scenarios.

api/server/controllers/UserController.js

@@ -36,6 +36,7 @@ const {
 const { updateUserPluginAuth, deleteUserPluginAuth } = require('~/server/services/PluginService');
 const { verifyEmail, resendVerificationEmail } = require('~/server/services/AuthService');
 const { getMCPManager, getFlowStateManager, getMCPServersRegistry } = require('~/config');
+const { invalidateCachedTools } = require('~/server/services/Config/getCachedTools');
 const { needsRefresh, getNewS3URL } = require('~/server/services/Files/S3/crud');
 const { processDeleteRequest } = require('~/server/services/Files/process');
 const { getAppConfig } = require('~/server/services/Config');
@@ -215,6 +216,7 @@ const updateUserPluginsController = async (req, res) => {
               `[updateUserPluginsController] Attempting disconnect of MCP server "${serverName}" for user ${user.id} after plugin auth update.`,
             );
             await mcpManager.disconnectUserConnection(user.id, serverName);
+            await invalidateCachedTools({ userId: user.id, serverName });
           }
         } catch (disconnectError) {
           logger.error(