feat(ios): upgrade button in setting (#13645)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- New Features
- Added a Subscription section in Mobile Settings (for signed-in users)
with plan info and an Upgrade button that opens the native paywall.
  - Supports showing “Pro” and “AI” paywalls.
  - Integrated native paywall provider on iOS.

- Style
- Introduced new styling for the subscription card, content, and button.

- Localization
- Added English strings for subscription title, description, and button.

- Chores
- Minor iOS project cleanup and internal wiring to enable the paywall
module.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/ios/src/plugins/paywall/definitions.ts

@@ -1,5 +1,5 @@
 export interface PayWallPlugin {
   showPayWall(options: {
-    type: string;
+    type: 'Pro' | 'AI';
   }): Promise<{ success: boolean; type: string }>;
 }