🧭 fix: Add Base Path Support for Login/Register and Image Paths (#10116)

* fix: add basePath pattern to support login/register and image paths

* Fix linter errors

* refactor: Update import statements for getBasePath and isEnabled, and add path utility functions with tests

- Refactored imports in addImages.js and StableDiffusion.js to use getBasePath from '@librechat/api'.
- Consolidated isEnabled and getBasePath imports in validateImageRequest.js.
- Introduced new path utility functions in path.ts and corresponding unit tests in path.spec.ts to validate base path extraction logic.

* fix: Update domain server base URL in MarkdownComponents and refactor authentication redirection logic

- Changed the domain server base URL in MarkdownComponents.tsx to use the API base URL.
- Refactored the useAuthRedirect hook to utilize React Router's navigate for redirection instead of window.location, ensuring a smoother SPA experience.
- Added unit tests for the useAuthRedirect hook to verify authentication redirection behavior.

* test: Mock isEnabled in validateImages.spec.js for improved test isolation

- Updated validateImages.spec.js to mock the isEnabled function from @librechat/api, ensuring that tests can run independently of the actual implementation.
- Cleared the DOMAIN_CLIENT environment variable before tests to avoid interference with basePath resolution.

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Co-authored-by: Danny Avila <danny@librechat.ai>

client/src/components/Auth/Login.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState } from 'react';
-import { ErrorTypes } from 'librechat-data-provider';
+import { ErrorTypes, registerPage } from 'librechat-data-provider';
 import { OpenIDIcon, useToastContext } from '@librechat/client';
 import { useOutletContext, useSearchParams } from 'react-router-dom';
 import type { TLoginLayoutContext } from '~/common';
@@ -104,7 +104,7 @@ function Login() {
           {' '}
           {localize('com_auth_no_account')}{' '}
           <a
-            href="/register"
+            href={registerPage()}
             className="inline-flex p-1 text-sm font-medium text-green-600 transition-colors hover:text-green-700 dark:text-green-400 dark:hover:text-green-300"
           >
             {localize('com_auth_sign_up')}