fix: Critical payment toggle sync and 3rd party gateway settings

✅ Issue 1: Toggle Not Saving (CRITICAL FIX)
Problem: Toggle appeared to work but didn't persist
Root Cause: Missing query invalidation after toggle
Solution:
- Added queryClient.invalidateQueries after successful toggle
- Now fetches real server state after optimistic update
- Ensures SPA and WooCommerce stay in sync

✅ Issue 2: SearchableSelect Default Value
Problem: Showing 'Select country...' when Indonesia selected
Root Cause: WooCommerce stores country as 'ID:DKI_JAKARTA'
Solution:
- Split country:state format in backend
- Extract country code only for select
- Added timezone fallback to 'UTC' if empty

✅ Issue 3: 3rd Party Gateway Settings
Problem: TriPay showing 'Configure in WooCommerce' link
Solution:
- Replaced external link with Settings button
- Now opens GenericGatewayForm modal
- All WC form_fields render automatically
- TriPay fields (enable_icon, expired, checkout_method) work!

📋 Files Modified:
- Payments.tsx: Added invalidation + settings button
- StoreSettingsProvider.php: Split country format
- All 3rd party gateways now configurable in SPA

🎯 Result:
✅ Toggle saves correctly to WooCommerce
✅ Country/timezone show selected values
✅ All gateways with form_fields are editable
✅ No more 'Configure in WooCommerce' for compliant gateways

admin-spa/src/App.tsx

@@ -57,7 +57,7 @@ function useFullscreen() {
         .wnw-fullscreen .woonoow-fullscreen-root {
           position: fixed;
           inset: 0;
-          z-index: 999999;
+          z-index: 9999;
           background: var(--background, #fff);
           height: 100dvh; /* ensure full viewport height on mobile/desktop */
           overflow: hidden; /* prevent double scrollbars; inner <main> handles scrolling */