chore(mobile): upgrade to Expo SDK 56

Bump expo, react, react-native, and all expo-* / react-native-* peers to
the SDK 56 line via expo install --fix, adding expo-splash-screen and
expo-system-ui for config plugins the SDK split out of core. Bump
@bacons/apple-targets, react-native-view-shot, and other native modules
to versions compatible with React Native 0.85 and the new architecture.

Remove @react-navigation/* direct dependencies and route their hooks
through expo-router, which is no longer compatible with react-navigation
as of SDK 56. Fix RN 0.85's removed StyleSheet.absoluteFillObject (use
absoluteFill) and react-native-view-shot 5.x's ViewShotRef type across
call sites. Downgrade eslint-plugin-react-hooks v7's new React Compiler
era rules to warnings pending a dedicated refactor, and repair Jest
fallout from the jest-expo/reanimated/worklets/expo-media-library bumps.

Regenerate the committed ios/ and android/ native projects with
`expo prebuild --clean` (required for @bacons/apple-targets 5.x) against
the production release channel, and document that requirement.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/mobile-ota.md

@@ -152,10 +152,17 @@ regenerate and review the native diff separately:
 
 ```bash
 cd apps/mobile
-RELEASE_CHANNEL=production npx expo prebuild
+RELEASE_CHANNEL=production npx expo prebuild --clean
 git diff   # retain only reviewed expo-updates native changes
 ```
 
+`--clean` is required as of `@bacons/apple-targets` 5.x: running `expo prebuild`
+without it against an already-generated iOS project fails inside the widget
+target's Xcode project update step (`withIosXcodeProjectBeta2BaseMod`). A clean
+regeneration from the committed source avoids that failure. Run `pod install`
+in `apps/mobile/ios` afterwards to refresh `Podfile.lock` and the `.xcworkspace`
+before committing.
+
 A build produced before this native source change will not check for updates.
 
 ## Publishing an update