Add guided setup screen and reconcile release plan

[StoneHub]

Summary

• implement selected Variant B as a native three-step Android Views setup screen
• preserve the existing SetupUiState and ScreenTimeoutController interfaces
• keep Android 13+ direct tile placement and Android 7-12 manual instructions
• fix the debug instrumentation package assertion
• add Matt workflow routing and triage docs
• reconcile the paid Play Store lane, free GitHub distribution, and signing backup gate

Design source

The selected prototype is preserved on codex/prototype-settings-screen at commit 1a7f12a.

Verification

• :app:compileDebugKotlin
• :app:compileDebugAndroidTestKotlin
• :app:testDebugUnitTest
• :app:assembleDebug
• git diff --check

Proof boundaries

• No device or emulator was connected, so this PR does not claim installed or visual runtime proof.
• Google Play publication has not happened.
• The second signing-key backup remains a hard blocker for version 1.1.1 or later GitHub releases.