Fix Kith iPhone-only TestFlight build

[sarthakagrawal927]

Summary

• make the Kith app target explicitly iPhone-only in the XcodeGen source and generated project
• document the personal-team App Store Connect record and accepted internal TestFlight upload
• preserve the separate unfinished PersonalSyncKit work in the primary checkout

Verification

• TARGETED_DEVICE_FAMILY = 1 in stable Xcode 26.6 release settings
• 9 unit tests passed
• 3 UI tests passed
• signed archive contains only UIDeviceFamily = [1]
• App Store Connect accepted Kith 1.0.0 (1) for processing under team 8F7LXHTJZR

Closes #4