fix: add progress logging during silent render pipeline stages (#1220)

* fix: add progress logging during silent render pipeline stages

The render pipeline only updates progress at stage boundaries (5%, 10%,
25%), leaving multi-minute gaps with zero log output on low-memory
hardware. This adds log.info calls at key sub-steps within the three
silent stages:

- Probe stage (5%): browser launch, session initialization, duration
  discovery, media asset discovery, audio volume automation, video
  visibility window detection
- Video extraction (10%): per-video extraction progress
- Calibration (25%): browser launch, session initialization,
  per-frame calibration progress, final cost estimate

Also adds 30-second heartbeat timers for the two initializeSession
calls (probe and calibration) that can individually take minutes on
constrained hardware.

Closes #1218

* fix: resolve CI failures in typecheck, runtime seek test, and timeline test

- Make handleGsapMaterializeKeyframes optional in DomEditSessionSlice
  and use optional chaining at the call site (not yet wired)
- Update GSAP adapter seek test to expect nudge+seek pattern
  (totalTime with suppressEvents:true followed by actual seek)
- Fix Timeline canvas height test to use TRACK_H constant (48)
  instead of stale hardcoded value (72)

* refactor: extract helpers to meet 600-line file size limit

- App.tsx (603→594): extract StudioToast component
- useDomEditSession.ts (688→600): extract useGsapSelectionHandlers hook
- Timeline.tsx (614→557): extract useTimelineAssetDrop hook
- PropertyPanel.tsx (647→584): extract TimingSection to propertyPanelTimingSection

* style: fix formatting in TimelineToolbar

packages/studio/src/player/components/Timeline.test.ts

@@ -12,6 +12,7 @@ import {
   shouldHandleTimelineDeleteKey,
   shouldAutoScrollTimeline,
 } from "./Timeline";
+import { RULER_H, TRACK_H } from "./timelineLayout";
 import { formatTime } from "../lib/time";
 
 describe("generateTicks", () => {
@@ -230,8 +231,7 @@ describe("getTimelinePlayheadLeft", () => {
 
 describe("getTimelineCanvasHeight", () => {
   it("includes bottom scroll buffer below the last track", () => {
-    // RULER_H (24) + trackCount * TRACK_H (48) + scroll buffer
-    expect(getTimelineCanvasHeight(3)).toBeGreaterThan(24 + 3 * 48);
+    expect(getTimelineCanvasHeight(3)).toBeGreaterThan(RULER_H + 3 * TRACK_H);
   });
 
   it("still keeps ruler space when there are no tracks", () => {