Feature/support expo 57

[marius-ck]

PR Description

Upgrades @bottom-tabs/expo-template to Expo SDK 57 (React Native 0.86.3, React 19.2.3, TypeScript 6.0.3).

Since SDK 56, Expo Router uses its own copy of React Navigation and rejects @react-navigation/* imports in app code. The template therefore switches from @bottom-tabs/react-navigation + withLayoutContext to @bottom-tabs/standard-navigation:

const Tabs = unstable_createStandardRouterNavigator(NativeBottomTabsContent, TabRouter);

Other changes:

• Dependencies aligned with SDK 57 (npx expo install --check and expo-doctor are clean). Dropped @react-navigation/native and added @react-native/jest-preset, which jest-expo 57 requires.
• DarkTheme, DefaultTheme and ThemeProvider are now imported from expo-router.
• useColorScheme maps React Native 0.86's 'unspecified' to 'light', so the Colors[scheme] lookups keep working.
• Removed newArchEnabled from app.json (dropped in SDK 55).
• Added "types": ["jest"] to tsconfig.json (TypeScript 6 no longer includes @types packages automatically).
• Fixed the IconSymbol mapping type for expo-symbols 57.
• yarn.lock: besides the upgrade, ran yarn dedupe '@typescript-eslint/*'. The bump left two 8.x versions, which stopped eslint-plugin-jest from being hoisted to the root, and lint crashed for the library packages (Environment key "jest/globals" is unknown). The example apps resolve the same packages as before.

No changes to react-native-bottom-tabs itself.

How to test?

Monorepo checks:

yarn install --immutable
yarn constraints
yarn turbo run lint typecheck test --force
yarn workspace @bottom-tabs/expo-template typecheck
yarn workspace @bottom-tabs/expo-template lint

Fresh app from the template. @bottom-tabs/standard-navigation isn't on npm until #581 is released, so pack the local packages:

yarn build
for p in expo-template standard-navigation react-native-bottom-tabs; do
  (cd packages/$p && npm pack --pack-destination /tmp/sdk57)
done
cd /tmp/sdk57
npx create-expo-app@latest app --template ./bottom-tabs-expo-template-*.tgz --no-install
cd app
# in package.json, point @bottom-tabs/standard-navigation and react-native-bottom-tabs at the file:../*.tgz tarballs
npm install
npx expo install --check && npx expo-doctor
npx expo start   # generates .expo/types, then stop it
npm run lint && npm run typecheck && npm test
npm run ios      # and npm run android

Screenshots