Release v0.2.3

[yvette-carlisle]

Summary

• bump Rsnap workspace packages and native-host fallback app version to 0.2.3
• update README and release validation docs for the v0.2.3 scroll-capture gate
• document toolbar Liquid Glass cadence, backdrop-change evidence, preview export latency, and copy cache timing as release-blocking checks

Verification

• cargo make fmt-toml-check
• bash -n scripts/build_and_run.sh scripts/release/sparkle-appcast.sh scripts/smoke/native-scroll-capture-macos.sh
• cargo metadata --format-version 1 --no-deps
• python3 /Users/x/.codex/plugins/cache/hack-ink/playbook/0.3.0/scripts/semantic_drift_audit.py --rev HEAD
• cargo make checks
• cargo make test-host-reset
• cargo make test-macos-native-host-stage
• SCROLL_START_METHOD=keyboard scripts/smoke/native-scroll-capture-macos.sh
• SCROLL_START_METHOD=toolbar scripts/smoke/native-scroll-capture-macos.sh
• SCROLL_START_METHOD=keyboard SCROLL_POINT_MODE=right_outside_selection MIN_SCROLL_COMMITS=4 MIN_EXPORT_GROWTH_PX=300 scripts/smoke/native-scroll-capture-macos.sh
• scripts/smoke/macos.sh
• scripts/perf/macos.sh

Scroll smoke evidence

• keyboard: 58 commits, 6825px growth, preview_refreshes=11, toolbar_gap_p95=23.73ms, duration_p95=0.03ms, changed_gap_p95=67.61ms
• toolbar: 52 commits, 6763px growth, preview_refreshes=11, toolbar_gap_p95=23.01ms, duration_p95=0.03ms, changed_gap_p95=66.75ms
• right_outside_selection: 54 commits, 6829px growth, preview_refreshes=12, toolbar_gap_p95=22.79ms, duration_p95=0.03ms, changed_gap_p95=67.44ms