feat: Tax route fix + Local Pickup + Email/Notifications settings

## 1. Fixed Tax Settings Route ✅
- Changed /settings/taxes → /settings/tax in nav tree
- Now matches App.tsx route
- Tax page now loads correctly

## 2. Advanced Local Pickup ✅
Frontend (LocalPickup.tsx):
- Add/edit/delete pickup locations
- Enable/disable locations
- Full address fields (street, city, state, postcode)
- Phone number and business hours
- Clean modal UI for adding locations

Backend (PickupLocationsController.php):
- GET /settings/pickup-locations
- POST /settings/pickup-locations (create)
- POST /settings/pickup-locations/:id (update)
- DELETE /settings/pickup-locations/:id
- POST /settings/pickup-locations/:id/toggle
- Stores in wp_options as array

## 3. Email/Notifications Settings ✅
Frontend (Notifications.tsx):
- List all WooCommerce emails
- Separate customer vs admin emails
- Enable/disable toggle for each email
- Show from name/email
- Link to WooCommerce for advanced config

Backend (EmailController.php):
- GET /settings/emails - List all emails
- POST /settings/emails/:id/toggle - Enable/disable
- Uses WC()->mailer()->get_emails()
- Auto-detects recipient type (customer/admin)

## Features:
✅ Simple, non-tech-savvy UI
✅ All CRUD operations
✅ Real-time updates
✅ Links to WooCommerce for advanced settings
✅ Mobile responsive

Next: Test all settings pages

admin-spa/src/nav/tree.ts

@@ -111,7 +111,7 @@ function getStaticFallbackTree(): MainNode[] {
         { label: 'Store Details', mode: 'spa' as const, path: '/settings/store' },
         { label: 'Payments', mode: 'spa' as const, path: '/settings/payments' },
         { label: 'Shipping & Delivery', mode: 'spa' as const, path: '/settings/shipping' },
-        { label: 'Taxes', mode: 'spa' as const, path: '/settings/taxes' },
+        { label: 'Tax', mode: 'spa' as const, path: '/settings/tax' },
         { label: 'Checkout', mode: 'spa' as const, path: '/settings/checkout' },
         { label: 'Customer Accounts', mode: 'spa' as const, path: '/settings/customers' },
         { label: 'Notifications', mode: 'spa' as const, path: '/settings/notifications' },