test(studio): cover expanded keyframe timeline

[miguel-heygen]

Summary

The expanded keyframe timeline is protected by focused regression coverage for layout, selection, dragging, retiming, and default expansion.

Stack

Part 14 of 20. Parent: #2580. Next: #2568. The golden reference, #2387, remains open and unchanged.

Test plan

• Integrated Studio suite: 2,800 tests passed
• Integrated parser suite: 853 tests passed
• Studio and parser typechecks passed
• Studio and parser production builds passed
• Per-PR CI completes on the submitted stack

Post-Deploy Monitoring & Validation

No additional operational monitoring required; this layer contains regression coverage only.

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[miguel-heygen]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• perf(studio-server): coordinate thumbnail generation #2658
• perf(studio): prioritize timeline thumbnail work #2657
• perf(studio): virtualize timeline thumbnail media #2656
• feat(studio): default to adaptive thumbnails #2655
• perf(cli): abort stale studio thumbnails #2654
• perf(studio): bound thumbnail decoding resources #2653
• perf(studio): schedule timeline thumbnail work #2652
• feat(studio): add timeline keyboard controls #2651
• feat(studio): coordinate logical timeline focus #2650
• feat(studio): expose timeline treegrid semantics #2649
• feat(studio): model logical timeline navigation #2648
• fix(studio): scope timeline ease focus requests #2647
• perf(studio): stabilize virtualized beat gestures #2646
• fix(studio): scope timeline context targets #2645
• perf(studio): virtualize timeline marquee selection #2644
• perf(studio): stabilize virtualized timeline drops #2643
• perf(studio): stabilize virtualized keyframe retiming #2642
• perf(studio): stabilize virtualized clip gestures #2641
• perf(studio): virtualize timeline clip windows #2640
• perf(studio): index timeline clip windows #2639
• perf(studio): virtualize timeline rows #2638
• perf(studio): centralize timeline viewport geometry #2637
• refactor(studio): decompose timeline orchestration #2636
• refactor(studio): extract timeline render contracts #2635
• refactor(studio): isolate clip drag lifecycle #2634
• test(studio): add timeline browser performance gate #2633
• test(studio): add timeline performance fixtures #2632
• perf(studio): define timeline viewport budgets #2631
• test(studio): cover keyframe edit identity fixes #2584
• fix(studio): harden keyframe edit identity #2583
• fix(parsers): preserve authored keyframe intent #2582
• fix(studio): switch ease modes optimistically #2570
• fix(studio): harden bulk keyframe editing #2581
• feat(studio): bulk-edit easing for merged keyframes #2568
• test(studio): cover expanded keyframe timeline #2567 👈 (View in Graphite)
• feat(studio): wire expanded keyframe timeline lanes #2580
• refactor(studio): consolidate animation inspector callbacks #2579
• feat(studio): add timeline keyframe callbacks #2578
• feat(studio): add keyframe track headers #2577
• feat(studio): add timeline property lanes #2576
• feat(studio): add timeline keyframe interactions #2575
• feat(studio): add variable timeline row geometry #2574
• feat(studio): add keyframe timeline state #2573
• feat(studio): add keyframe ease inspector #2562
• feat(studio): add keyframe ease controls #2572
• feat(core): add deterministic keyframe ease runtime #2561
• feat(studio): make timeline thumbnails opt-in #2559
• fix(core): install runtime bridge after transport setup #2558
• main

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