v0.2.43

Fixes transcript runway scrolling regressions:

• First sends, subsequent messages, and steering messages glide smoothly into position.
• Streaming content consumes the runway immediately and follows automatically once it fills the available space.
• Downward scrolling no longer enters a temporary empty region that snaps back.
• Scrolling down during a short runway keeps following later output; scrolling up releases it.
• Returning after background streaming preserves downward scrolling and user control.

Validation: 613 UI tests passed locally and in GitHub CI. Eight matched Linux replays against v0.2.41 found no material CPU or memory regression. Native macOS performance was not remeasured.

Videos, regression coverage, and measurements: #261, #262.

Full changelog: v0.2.41...v0.2.43