Here is the modified code.

### Changes Made:
1.  **Vendor Page Redirection Logic**:
    *   In `paaf_handle_form_submission`: I updated the redirect logic. Before redirecting, it checks if a `vendor_code` was found. If yes, it queries the `mvcm_vendors` table to see if that vendor has a `vendor_page_id`.
    *   If a page ID exists, the user is redirected to that specific vendor's page.
    *   If no page is set for the vendor, it falls back to the default `affiliate-code-redeemed` page.
2.  **User Data Attachment**: The code continues to properly update `user_meta` with `vendor_code` and adds the user to `mvcm_vendor_customers` (with `vendor_name`) to ensure the relationship is stored.

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