feat(native): TREK on Apple Watch, with complications

A watchOS app embedded in the iPhone app: today's next stop with its
countdown, the next booking with reference, seat and platform, the trip
with its days and places (Directions into Apple Maps), and the packing
list and to-dos to tick off. The phone sends the snapshot through
WatchConnectivity; ticks go back as queued user info. Three
complications (next stop, countdown, trip day) in every accessory family,
scored for the Smart Stack. 28 languages.

The native workflow captures every screen from watchOS simulators in a
screenshot mode, on the largest and the smallest watch.

.github/workflows/native.yml

@@ -17,6 +17,7 @@ on:
       - 'client/ios/**'
       - 'client/native-shell/**'
       - 'client/src/native/trekShell.ts'
+      - 'client/src/native/watch.ts'
       - 'client/src/native/serverAddress.ts'
       - 'client/capacitor.config.ts'
       - 'client/vite.native.config.js'
@@ -103,7 +104,7 @@ jobs:
           xcodebuild -version
 
       - name: Check the property lists
-        run: plutil -lint client/ios/App/App/Info.plist client/ios/ExportOptions.plist client/ios/App/NotificationService/Info.plist client/ios/App/NotificationService/NotificationService.entitlements client/ios/App/App/App.entitlements client/ios/App/TREKWidgets/Info.plist client/ios/App/TREKWidgets/TREKWidgets.entitlements client/ios/App/TREKWidgets/*.lproj/Localizable.strings client/ios/App/ShareExtension/Info.plist client/ios/App/ShareExtension/ShareExtension.entitlements client/ios/App/ShareExtension/*.lproj/Localizable.strings
+        run: plutil -lint client/ios/App/App/Info.plist client/ios/ExportOptions.plist client/ios/App/NotificationService/Info.plist client/ios/App/NotificationService/NotificationService.entitlements client/ios/App/App/App.entitlements client/ios/App/TREKWidgets/Info.plist client/ios/App/TREKWidgets/TREKWidgets.entitlements client/ios/App/TREKWidgets/*.lproj/Localizable.strings client/ios/App/ShareExtension/Info.plist client/ios/App/ShareExtension/ShareExtension.entitlements client/ios/App/ShareExtension/*.lproj/Localizable.strings client/ios/App/TREKWatch/Info.plist client/ios/App/TREKWatch/TREKWatch.entitlements client/ios/App/TREKWatch/*.lproj/Localizable.strings client/ios/App/TREKWatchWidgets/Info.plist client/ios/App/TREKWatchWidgets/TREKWatchWidgets.entitlements
 
       - uses: actions/setup-node@v6
         with:
@@ -120,6 +121,8 @@ jobs:
         working-directory: client
         run: npm run cap:sync -- ios
 
+      # No -sdk: the scheme builds the embedded watch app and its complications
+      # against the watchOS simulator SDK and the rest against the iOS one.
       - name: Build for the simulator
         working-directory: client/ios/App
         run: |
@@ -127,7 +130,6 @@ jobs:
             -project App.xcodeproj \
             -scheme App \
             -configuration Debug \
-            -sdk iphonesimulator \
             -destination 'generic/platform=iOS Simulator' \
             CODE_SIGNING_ALLOWED=NO
 
@@ -159,3 +161,72 @@ jobs:
           name: widget-previews
           path: client/ios/WidgetPreviews/out
           retention-days: 14
+
+  # The watch's half in the UI (client/src/native/watch.ts): the snapshot it
+  # builds and the ticks it takes back, typechecked and tested here as well,
+  # so a change to the bridge is checked next to the Swift that reads it.
+  watch-bridge:
+    runs-on: ubuntu-24.04
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version-file: .nvmrc
+          cache: npm
+
+      - name: Install
+        run: npm ci --workspace=shared --workspace=client
+
+      - name: Build shared
+        run: npm run build --workspace=shared
+
+      - name: Typecheck the client
+        working-directory: client
+        run: npm run typecheck
+
+      - name: Test the widget and watch snapshots
+        working-directory: client
+        run: npx vitest run src/native/watch.test.ts src/native/widgets.test.ts src/native/widgetExtras.test.ts
+
+  # The watch app on watchOS simulators in its screenshot mode (DemoMode.swift):
+  # every screen on the largest and the smallest watch, the main ones in every
+  # language, and the complications, as PNGs to look at without a watch.
+  watch-screens:
+    runs-on: macos-15
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Select Xcode 26
+        run: |
+          XCODE=$(ls -d /Applications/Xcode_26*.app | sort -V | tail -1)
+          test -n "$XCODE"
+          sudo xcode-select -s "$XCODE"
+
+      - name: Make sure a watchOS simulator runtime is there
+        run: |
+          xcrun simctl list runtimes | grep -q watchOS || xcodebuild -downloadPlatform watchOS
+          xcrun simctl list runtimes
+
+      - name: Build the watch app for the simulator
+        working-directory: client/ios/App
+        run: |
+          xcodebuild build \
+            -project App.xcodeproj \
+            -target TREKWatch \
+            -configuration Debug \
+            -sdk watchsimulator \
+            SYMROOT="$PWD/build" \
+            CODE_SIGNING_ALLOWED=NO
+
+      - name: Capture the screens
+        run: bash client/ios/scripts/watch-screens.sh client/ios/App/build/Debug-watchsimulator/TREKWatch.app "$PWD/watch-screens"
+
+      - uses: actions/upload-artifact@v6
+        if: always()
+        with:
+          name: watch-screens
+          path: watch-screens
+          retention-days: 14