feat(mobile): disable swipe back gesture when there is no back in header (#8876)

close AF-1663, AF-1756

- new global `ModalConfigContext`
- new logic to judge whether inside modal
- render `✕` for PageHeader back if inside modal
- only enable `NavigationGesture` when there is `<` in PageHeader

packages/frontend/apps/ios/src/plugins/navigation-gesture/definitions.ts

@@ -0,0 +1,5 @@
+export interface NavigationGesturePlugin {
+  isEnabled: () => Promise<boolean>;
+  enable: () => Promise<void>;
+  disable: () => Promise<void>;
+}

packages/frontend/apps/ios/src/plugins/navigation-gesture/index.ts

@@ -0,0 +1,9 @@
+import { registerPlugin } from '@capacitor/core';
+
+import type { NavigationGesturePlugin } from './definitions';
+
+const NavigationGesture =
+  registerPlugin<NavigationGesturePlugin>('NavigationGesture');
+
+export * from './definitions';
+export { NavigationGesture };