Keep transcript tail visible above keyboard

[R055LE]

Summary

• keep a followed transcript tail anchored when the software keyboard resizes the viewport
• preserve deliberate scrolling into older output and existing raw-terminal IME handling
• record the source fix and pending Samsung acceptance

Verification

• targeted real-Gboard regression failed before the fix and passed afterward
• connectedDebugAndroidTest: 76 tests completed, 3 opt-in fixture/performance tests skipped
• test lint assembleDebug assembleRelease