Watch: TestFlight archive, iOS stub container, testflight.sh

The App Store only accepts a watch-only app inside an empty iOS stub
(watchapp2-container), the pair Xcode's Watch-only App template makes.
The stub takes org.gbrown.wristcode; the watch app, and so the APNs topic,
becomes org.gbrown.wristcode.watchkitapp.

Adds ITSAppUsesNonExemptEncryption = NO and scripts/testflight.sh, which
archives with API key automatic signing and a timestamp build number,
then exports and uploads (or exports only with --no-upload).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

watch/WristCode/Info.plist

@@ -20,6 +20,8 @@
 	<string>$(MARKETING_VERSION)</string>
 	<key>CFBundleVersion</key>
 	<string>$(CURRENT_PROJECT_VERSION)</string>
+	<key>ITSAppUsesNonExemptEncryption</key>
+	<false/>
 	<key>WKApplication</key>
 	<true/>
 	<key>WKWatchOnly</key>