Summary

• Eliminates all 7 circular dependency cycles in packages/studio/src/
• Fixes a runtime rules-of-hooks violation (useMemo after early return in App.tsx) that caused "Rendered more hooks than during the previous render" error

Changes

Rules-of-hooks fix: Moved useMemo for timelineToolbar before the early return in App.tsx so hook count is stable across renders.

Circular dep fixes (14 files, net -10 LOC):

• Extracted shared types to domEditCommitTypes.ts to break useDomEditCommits ↔ useDomEditPositionPatchCommit/useDomEditTextCommits cycles
• Restructured DomEditOverlay gesture imports to break overlay ↔ gesture handler cycles
• Changed barrel file imports (../player) to direct source imports to break player/index.ts cycles
• Extracted COMPOSITION_ROOT_REGEX to compositionPatterns.ts to break studioHelpers ↔ timelineAssetDrop cycle
• Restructured useTimelineEditing ↔ useRazorSplit imports

Verification

• npx madge --circular packages/studio/src/App.tsx → 0 circular dependencies (was 7)
• bun run --cwd packages/studio typecheck → pass
• bun run --cwd packages/studio test → 796 tests pass
• Browser QA: studio loads, play/pause works, composition switching works, timeline clip selection works, code editor works, inspector panel works

Test plan

• bun run --cwd packages/studio typecheck passes
• bun run --cwd packages/studio test passes
• Studio loads without "Rendered more hooks" error
• Play/pause, composition switch, element selection all work