BizCore v6.4 - Mundo Seller Onboarding & Shop Workspace

SAFE ADDITIVE UPDATE
- No existing BizCore/Mundo records are deleted or reset.
- Public Become a Seller -> Admin Review -> Approve -> Seller shop shell provisioned.
- Review actions require the current BizCore user's password.
- Request Changes supports applicant edit/resubmit.
- Seller dashboard adds order/product/earnings KPIs.
- Seller can upload shop logo, banner and product images.
- Seller product listings continue to require marketplace review before live publishing.
- Courier mode remains Platform Managed by default. Seller Managed can still only be enabled by admin.

Install:
1. Extract this ZIP into the ceylongemx.online root and overwrite matching files.
2. Open /update-6.4.php as Super Admin.
3. Test Become a Seller -> Seller Applications -> Approve & Create Shop -> Status -> Activate Seller Account.
