refactor(studio): simplify hooks, split contexts, remove dead code (#1416)

* fix(studio): guard Zustand no-op setters and fix useConsoleErrorCapture memory leak

- Guard setIsPlaying to skip set() when value unchanged (eliminates 60
  notifications/sec during reverse playback)
- Guard caption store selectGroup to bail before set() when group missing
  (prevents empty Zustand notifications)
- Guard clearSelection to skip when already empty
- Fix useConsoleErrorCapture: restore original console.error, remove error
  event listener, and delete __hfErrorCapture flag on cleanup

* fix(studio): delete dead files and unused exports

Remove 7 dead files (audioBeatDetection, keyframeSnapping,
timelineInspector, DopesheetStrip, StaggerControls,
TimelineLayerPanel, TimelineEditorNotice) and their test companions.

Delete unused computeFitToChildrenSize export from propertyPanelHelpers.

Fix re-export indirection: useDomEditCommits and studioMotionOps.test
now import patch builders directly from manualEditsDomPatches instead
of the re-export passthrough in manualEditsDom.

* fix(studio): eliminate effect-chain state mirroring for lint findings, hover, and GSAP fetch

Move lint findingsByElement sync from App.tsx into useLintModal where
the value is produced, removing the mirroring useEffect. Consolidate
4 hover-clearing effects in useDomSelection into 2 (one unconditional
on context change, one conditional combining caption mode, selection
match, and disconnected element checks). Fold the GSAP retry effect
into the fetch effect in useGsapTweenCache, scheduling a single retry
via setTimeout when the initial fetch returns 0 animations.

Eliminates 3 unnecessary render cycles from effect chains.

* fix(studio): memoize renderQueue, toolbar, and canvas rect to prevent re-render cascade

- Wrap renderQueue object in useMemo so StudioContext consumers don't
  re-render on every App render
- Memoize timelineToolbar JSX so NLELayout memo isn't defeated
- Move canvasRect getBoundingClientRect() from render-time IIFE to a
  useLayoutEffect-backed ref, eliminating layout thrashing
- Track and clear setTimeout handles in refreshPreviewDocumentVersion
  to prevent stale timer accumulation on rapid calls and unmount

* refactor(studio): consolidate GSAP shared primitives — defaults, iframe access, keyframe parsing

Extract duplicated PROPERTY_DEFAULTS, IframeGsap interface, iframe
accessors (getIframeGsap, queryIframeElement), percentage keyframe
parsing, and toAbsoluteTime into a single gsapShared.ts module.

Removes ~120 lines of copy-pasted logic across 8 hook files, reducing
drift risk between the duplicate implementations.

* fix(studio): remove dead store fields, dead file, duplicate helper, and unsafe assertions

* refactor(studio): deduplicate selector helpers, rounding utils, percentage computation, and iframe access

* fix(studio): split StudioContext into Shell + Playback to prevent cascade re-renders

* refactor(studio): decompose useGsapScriptCommits into focused mutation hooks

* refactor(studio): decompose useFileManager into focused file operation hooks

Extract useFileTree (tree loading, refresh, derived assets/compositions)
and useEditorSave (debounced save with history tracking) from the 508-LOC
useFileManager. The parent hook composes both and retains file I/O,
click-to-source, upload/import, and CRUD — preserving the same public
interface so no consumers change.

* refactor(studio): decompose useDomEditCommits into focused commit hooks

Extract geometry (path offset, box size, rotation) and element lifecycle
(delete, z-index reorder) into useDomGeometryCommits and
useElementLifecycleOps. Parent keeps persistDomEditOperations as core
and composes all sub-hooks — public interface unchanged.

* refactor(studio): simplify useAppHotkeys with declarative command table

* refactor(studio): simplify useAppHotkeys with declarative command table

Replace 15 individual useRef callback refs with a single cbRef object.
Extract keydown dispatch into pure dispatchModifierKey/dispatchPlainKey
functions. Merge duplicate undo/redo logic into shared applyHistory.
Extract cross-origin listener boilerplate into safeAddListener/safeRemoveListener.

Hook body: 204 LOC (down from 445). Public API unchanged.

* fix(studio): remove unused getDomEditTargetKey import

* refactor(studio): decompose useDomEditSession into focused editing hooks

Extract GSAP-aware geometry intercepts (move/resize/rotation) and
animated property commit into useGsapAwareEditing, and selection
wiring, GSAP cache management, preview sync, and selection handlers
into useDomEditWiring. The parent remains a pure composition shell.

* style(studio): fix formatting in 5 files

* fix(studio): trim App.tsx to 598 lines (under 600 limit)

---------

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

packages/studio/src/hooks/useDomSelection.ts

@@ -389,47 +389,30 @@ export function useDomSelection({
 
   // ── Effects ──
 
-  // Clear hover on caption mode change
-  // eslint-disable-next-line no-restricted-syntax
-  useEffect(() => {
-    if (captionEditMode) updateDomEditHoverSelection(null);
-  }, [captionEditMode, updateDomEditHoverSelection]);
-
-  // Clear hover on composition/project/preview change
+  // Clear hover unconditionally on composition/project/preview change
   // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {
     updateDomEditHoverSelection(null);
   }, [activeCompPath, projectId, previewIframe, refreshKey, updateDomEditHoverSelection]);
 
-  // Clear hover when matching selection
+  // Clear hover conditionally (caption mode, matches selection, disconnected element)
   // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {
     if (!domEditHoverSelection) return;
-    const hoverMatchesSelection = domEditSelectionsTargetSame(
-      domEditHoverSelection,
-      domEditSelection,
-    );
-    const hoverMatchesGroup = domEditSelectionInGroup(
-      domEditGroupSelections,
-      domEditHoverSelection,
-    );
-    if (!hoverMatchesSelection && !hoverMatchesGroup) return;
-    updateDomEditHoverSelection(null);
+    const shouldClear =
+      captionEditMode ||
+      domEditSelectionsTargetSame(domEditHoverSelection, domEditSelection) ||
+      domEditSelectionInGroup(domEditGroupSelections, domEditHoverSelection) ||
+      !domEditHoverSelection.element.isConnected;
+    if (shouldClear) updateDomEditHoverSelection(null);
   }, [
-    domEditGroupSelections,
+    captionEditMode,
     domEditHoverSelection,
     domEditSelection,
+    domEditGroupSelections,
     updateDomEditHoverSelection,
   ]);
 
-  // Clear hover when element disconnected
-  // eslint-disable-next-line no-restricted-syntax
-  useEffect(() => {
-    if (!domEditHoverSelection) return;
-    if (domEditHoverSelection.element.isConnected) return;
-    updateDomEditHoverSelection(null);
-  }, [domEditHoverSelection, updateDomEditHoverSelection]);
-
   // Clear selection on caption mode change
   // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {