feat: implement upgrade to premium flow

This commit adds the ability for tenants to upgrade their package directly from the mobile billing page. It includes:
- New API function createTenantPaddleCheckout in api.ts
- Upgrade handler and UI in BillingPage.tsx
- Updated navigation in EventAnalyticsPage.tsx to link to the packages section of the billing page

resources/js/admin/mobile/EventAnalyticsPage.tsx

@@ -66,7 +66,7 @@ export default function MobileEventAnalyticsPage() {
           </YStack>
           <CTAButton
             label={t('analytics.upgradeAction', 'Upgrade to Premium')}
-            onPress={() => navigate(adminPath('/mobile/billing'))}
+            onPress={() => navigate(adminPath('/mobile/billing#packages'))}
           />
         </MobileCard>
       </MobileShell>