feat: Add the frontend support for MFA (#12372)

FE support for https://github.com/chatwoot/chatwoot/pull/12290
## Linear:
- https://github.com/chatwoot/chatwoot/issues/486

## Description
This PR implements Multi-Factor Authentication (MFA) support for user
accounts, enhancing security by requiring a second form of verification
during login. The feature adds TOTP (Time-based One-Time Password)
authentication with QR code generation and backup codes for account
recovery.

## Type of change

- [ ] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

- Added comprehensive RSpec tests for MFA controller functionality
- Tested MFA setup flow with QR code generation
- Verified OTP validation and backup code generation
- Tested login flow with MFA enabled/disabled

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Pranav <pranav@chatwoot.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/v3/api/auth.js

@@ -13,6 +13,16 @@ export const login = async ({
 }) => {
   try {
     const response = await wootAPI.post('auth/sign_in', credentials);
+
+    // Check if MFA is required
+    if (response.status === 206 && response.data.mfa_required) {
+      // Return MFA data instead of throwing error
+      return {
+        mfaRequired: true,
+        mfaToken: response.data.mfa_token,
+      };
+    }
+
     setAuthCredentials(response);
     clearLocalStorageOnLogout();
     window.location = getLoginRedirectURL({
@@ -20,8 +30,17 @@ export const login = async ({
       ssoConversationId,
       user: response.data.data,
     });
+    return null;
   } catch (error) {
+    // Check if it's an MFA required response
+    if (error.response?.status === 206 && error.response?.data?.mfa_required) {
+      return {
+        mfaRequired: true,
+        mfaToken: error.response.data.mfa_token,
+      };
+    }
     throwErrorMessage(error);
+    return null;
   }
 };