chore(deps): migrate to Expo SDK 56 (Phase 1 - compat)

Compatibility migration from SDK 55 to SDK 56 (react-native-tvos 0.85.3-0,
React 19.2.3). Phase 1 = breaking changes needed to build; new-feature
adoption and TypeScript 6 are deferred to Phase 2.

- Deps aligned to SDK 56 via `expo install --fix` (all expo-* 56.x, screens
  4.25.2, reanimated 4.3.1, worklets 0.8.3, gesture-handler 2.31.x, svg 15.15.4)
- react-native -> react-native-tvos@0.85.3-0; react/react-dom 19.2.3
- expo-router forked React Navigation: ran the SDK 56 codemod
  (@react-navigation/* imports -> expo-router/*), removed the 3 now-unused
  direct @react-navigation/* dependencies, retyped NestedTabPageStack via
  expo-router Stack.Screen options
- StyleSheet.absoluteFillObject -> absoluteFill (removed from RN 0.85 types)
- app.json ios.deploymentTarget 15.6 -> 16.4 (SDK 56 minimum)
- CI: Xcode 26.2 -> 26.4; made xcode-version Renovate-managed via a
  customManager + xcodereleases customDatasource
- @babel/core 7.29.7; dropped version-locked screens/codegen bun-patches
  (no longer applicable on SDK 56)

Deferred to Phase 2: TypeScript 6 (toolchain: @types/node, jest globals,
UdpSocket typing), @expo/vector-icons -> @react-native-vector-icons codemod.

typecheck passes. expo-doctor: 2 known failures remain (react-native-track-player
New Arch fork; typescript major mismatch pending the deferred TS6 bump).

.github/workflows/build-apps.yml

@@ -218,7 +218,8 @@ jobs:
       - name: 🔧 Setup Xcode
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1
         with:
-          xcode-version: "26.2"
+          # renovate: datasource=custom.xcode depName=xcode versioning=loose
+          xcode-version: "26.4"
 
       - name: 🏗️ Setup EAS
         uses: expo/expo-github-action@b184ff86a3c926240f1b6db41764c83a01c02eef # main
@@ -282,7 +283,8 @@ jobs:
       - name: 🔧 Setup Xcode
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1
         with:
-          xcode-version: "26.2"
+          # renovate: datasource=custom.xcode depName=xcode versioning=loose
+          xcode-version: "26.4"
 
       - name: 🚀 Build iOS app
         env:
@@ -341,7 +343,8 @@ jobs:
       - name: 🔧 Setup Xcode
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1
         with:
-          xcode-version: "26.2"
+          # renovate: datasource=custom.xcode depName=xcode versioning=loose
+          xcode-version: "26.4"
 
       - name: 🏗️ Setup EAS
         uses: expo/expo-github-action@b184ff86a3c926240f1b6db41764c83a01c02eef # main
@@ -408,7 +411,8 @@ jobs:
       - name: 🔧 Setup Xcode
         uses: maxim-lobanov/setup-xcode@ed7a3b1fda3918c0306d1b724322adc0b8cc0a90 # v1
         with:
-          xcode-version: "26.2"
+          # renovate: datasource=custom.xcode depName=xcode versioning=loose
+          xcode-version: "26.4"
 
       - name: 🚀 Build iOS app
         env: