PHONE DISPLAY MANAGER v2

Default login:
username: admin
password: admin123

NEW:
- Bulk price removed.
- Compatible model now has its own brand_id.
- One display can be compatible with models from ANY brand.
- Example: OPPO display -> Realme 8, Realme 9, Vivo Y...
- Compatible model has brand + typed model name.
- Change Password page included.

NEW INSTALL:
Import schema.sql into a NEW database.

UPGRADE EXISTING DATABASE:
1. Backup database.
2. Import migrate_existing.sql.
3. If the old products table does not have bulk_price, remove that ALTER statement.
4. Existing compatibility records are initially assigned the display's own brand. Edit them afterward where cross-brand compatibility applies.

Requirements: PHP 8+, MySQL/MariaDB, mysqli.


NEW FEATURES - PASSWORD & DELIVERY STOCK
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1. Import password_reset_migration.sql into the existing database.
2. Users can change their password after login.
3. Users can use Forgot Password from the login page.
4. Reset links expire after 1 hour and are single-use.
5. Admin delivery updates now adjust products.quantity by the DELIVERY DIFFERENCE only.
6. Increasing delivered quantity deducts stock; reducing delivered quantity restores stock.
7. Delivery is rejected if there is insufficient stock.
8. Delivery updates are transactional and lock the affected rows to prevent double deduction.
