feat: Implement Phase 1 Shopify-inspired settings (Store, Payments, Shipping)

✨ Features:
- Store Details page with live currency preview
- Payments page with visual provider cards and test mode
- Shipping & Delivery page with zone cards and local pickup
- Shared components: SettingsLayout, SettingsCard, SettingsSection, ToggleField

🎨 UI/UX:
- Card-based layouts (not boring forms)
- Generous whitespace and visual hierarchy
- Toast notifications using sonner (reused from Orders)
- Sticky save button at top
- Mobile-responsive design

🔧 Technical:
- Installed ESLint with TypeScript support
- Fixed all lint errors (0 errors)
- Phase 1 files have zero warnings
- Used existing toast from sonner (not reinvented)
- Updated routes in App.tsx

📝 Files Created:
- Store.tsx (currency preview, address, timezone)
- Payments.tsx (provider cards, manual methods)
- Shipping.tsx (zone cards, rates, local pickup)
- SettingsLayout.tsx, SettingsCard.tsx, SettingsSection.tsx, ToggleField.tsx

Phase 1 complete: 18-24 hours estimated work

admin-spa/src/components/DummyDataToggle.tsx

@@ -15,13 +15,14 @@ export function DummyDataToggle() {
   const location = useLocation();
   const isDashboardRoute = location.pathname === '/' || location.pathname.startsWith('/dashboard');
 
-  // Use dashboard context for dashboard routes, otherwise use local state
-  const dashboardContext = isDashboardRoute ? useDashboardContext() : null;
+  // Always call hooks unconditionally
+  const dashboardContext = useDashboardContext();
   const localToggle = useDummyDataToggle();
 
-  const useDummyData = isDashboardRoute ? dashboardContext!.useDummyData : localToggle.useDummyData;
+  // Use dashboard context for dashboard routes, otherwise use local state
+  const useDummyData = isDashboardRoute ? dashboardContext.useDummyData : localToggle.useDummyData;
   const toggleDummyData = isDashboardRoute
-    ? () => dashboardContext!.setUseDummyData(!dashboardContext!.useDummyData)
+    ? () => dashboardContext.setUseDummyData(!dashboardContext.useDummyData)
     : localToggle.toggleDummyData;
 
   // Only show in development (always show for now until we have real data)