feat(editor): keystroke overlay — render layer + persistence (Part 2/3)

[starkdcc]

Keystroke overlay — Part 2 of 3 (render layer + persistence)

Stacked on webadderallorg#733 (capture + display foundation). Based on the feat/keystroke-overlay-foundation branch so this diff shows only Part 2's changes — review webadderallorg#733 first.

What's in this PR (all tsc + Biome clean; 25 pure-core tests pass)

• Settings persistence — showKeystrokes / keystrokePosition / keystrokeSize added to ProjectEditorState + editorPreferences, normalized and defaulted (off / bottom-center / 1×), mirroring the cursor prefs.
• PixiKeystrokeOverlay — a self-contained PIXI render layer mirroring PixiCursorOverlay's construct/update/reset/destroy contract, driven entirely by the tested coalescing core. Pooled Graphics + Text keycaps, screen-anchored (bottom/top, L/C/R), size-scaled, per-group fade. Type-checked against PixiJS v8.
• detectGlyphStyle() — platform-aware ⌘/Ctrl/Win/Super (guarded for Node).
• Keystroke sidecar persistence primitives — getKeystrokePathForVideo (.keystrokes.json) + normalize/write/persistPending/snapshot keystroke telemetry, exact mirrors of the cursor telemetry functions.

Remaining wiring (Part 3/3 — needs a local dev loop to verify)

The pieces below are pure integration/threading. I have exact anchors for each (from a code-map pass); they compile in isolation but must be verified in npm run dev:

• Enable capture: thread a { showKeystrokes } option through preload.setRecordingState + electron-env.d.ts + the set-recording-state handler → call the (already-existing) setIsKeystrokeCaptureActive(...) in the start branch; setIsKeystrokeCaptureActive(false) + snapshotKeystrokeTelemetryForPersistence() in every stop branch (native-win @994/996, set-recording-state stop @1838, + any mac/ffmpeg stop paths — grep snapshotCursorTelemetryForPersistence).
• Read path: add get-keystroke-telemetry IPC (mirror get-cursor-telemetry) + preload.getKeystrokeTelemetry + electron-env.d.ts type.
• Renderer state: VideoEditor — keystrokeTelemetry state + a loadKeystrokeTelemetry effect (mirror the videoSourcePath-keyed cursor effect including its fresh-recording retry loop), then pass keystrokeTelemetry + showKeystrokes/position/size to VideoPlayback.
• VideoPlayback: declare the props; create a keystrokeContainer sibling of cursorContainer; instantiate PixiKeystrokeOverlay; attach at both mount sites (~2197/2297); .update(samples, timeMs, baseMaskRef.current, showKeystrokes, freeze) per frame (~2547); .destroy() in cleanup.
• Settings UI: SettingsPanel case "cursor" — a "Show Keystrokes" Switch + position Select + size SliderControl, 3 props + defaults, and effects.* i18n keys in all 10 locale settings.json files.
• Sidecar cleanup: unlink the .keystrokes.json alongside the cursor sidecar in project.ts + prune.ts.
• (optional) export parity: draw the overlay in frameRenderer.ts / modernFrameRenderer.ts so keystrokes appear in MP4/GIF exports.

Manual test plan (once Part 3 lands)

1. Enable "Show Keystrokes"; record; type text + shortcuts (⌘C / Ctrl+Shift+P); stop.
2. In the editor: keycaps appear at the chosen anchor, chords group, rapid typing merges into a word, groups fade after ~1.2s, and scrubbing reveals keys at the right times.
3. Reopen the .recordly project → overlay replays (sidecar persisted).
4. Export MP4/GIF → keystrokes burned in (if export parity added).
5. Privacy: with the toggle off, confirm no .keystrokes.json is written.

Notes

• Privacy by design: capture is gated on a default-off flag; nothing is recorded unless the overlay is enabled.
• Developed with AI assistance (disclosed in commit trailers). Happy to reshape scope or fold parts together.