feat: enhance Mini App design guidelines and refactor layout components

- Updated Mini App design guidelines to include detailed instructions on UI changes, accessibility rules, and verification processes.
- Refactored multiple components to utilize `MiniAppScreen` and `MiniAppScreenContent` for consistent layout structure across the application.
- Improved error handling in `GlobalError` and `NotFound` components by integrating new layout components for better user experience.
- Introduced new hooks for admin functionality, streamlining access checks and data loading processes.
- Enhanced documentation to reflect changes in design policies and component usage, ensuring clarity for future development.

webapp-next/src/lib/telegram-interaction-policy.ts

@@ -0,0 +1,16 @@
+/**
+ * Telegram interaction policy for Mini App behavior.
+ * Keep this as a single source of truth for platform UX decisions.
+ */
+
+/**
+ * Keep vertical swipes enabled unless a specific screen has a hard conflict
+ * with Telegram swipe-to-minimize behavior.
+ */
+export const DISABLE_VERTICAL_SWIPES_BY_DEFAULT = false;
+
+/**
+ * Show closing confirmation only for stateful flows where user choices can be
+ * lost by accidental close/minimize.
+ */
+export const ENABLE_CLOSING_CONFIRMATION_FOR_STATEFUL_ADMIN_FLOW = true;