Fix RSVP chapter progress and sweep restoration

[Steadyx]

What changed

Reader and RSVP now use the same source-word chapter progress: opening RSVP at 75% through a chapter remains at 75%, regardless of the book-wide percentage or the playback starting point.

RSVP sweep navigation now covers the full current chapter after a midway launch, saved-state restoration, landscape/portrait layout changes, and settings reloads. The drag handler reads the current playback context rather than retaining an earlier frame list.

Full navigation reuses the cached chapter generation. When the selected word falls inside a grouped unit, only that unit is split around the selection; the remaining chapter retains its cached segmentation. Playback effects and indexing run off the UI thread, and startup timing stays attached to the selected position.

Risk

Source-frame alignment and startup ramps are the main sensitive areas. Unit and device regressions cover exact split-word restoration, complete source-word coverage, forward/backward sweep bounds, resumed timing, progress parity, presets, and punctuation holds. Sweep remains scoped to the current chapter. Device rotation coverage combines portrait/landscape-sized layouts with saved-state recreation.

Validation

• ./gradlew qualityCheck — 840 unit tests passed
• ./gradlew qualityGate — passed on the final commit, including Android Lint and APK assembly
• Focused regression tests added for chapter progress, complete navigation bounds, cached generation reuse, bounded grouped-unit rebuilding, and startup/resume timing
• git diff --check
• 11 connected Android device checks passed: 2 sweep/performance tests plus 9 existing progress, playback, preset, split-word, and punctuation tests

On the connected CPH2493 / Android 16 debug build, a 5,000-word single-word-frame fixture took 1,069 ms for cold preparation and 30/23/25 ms for cached reload preparation. These are observational timings, not universal latency guarantees. Frame preparation runs off the UI thread; swipes use the prepared frame list.

Quality policy

• No baseline, ignoreFailures, broad exclusion, or unrelated threshold relaxation was added
• No new suppression was added
• No generated files, debug logging, commented-out code, or unrelated formatting churn is included in production code