- POS Terminal now shows products tab with addProduct() method
  (programs are enrolled via receptionist desk, not POS)
- Product list and POS show branch products + academy-wide (null branch)
- CreateProductWizard and ProductForm now set branch_id on create
- Product model gets ManglesUniqueOnDelete for SKU collision prevention
- Clicking a product in POS adds it to cart (or increments qty if exists)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>