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/captions/store.ts

@@ -59,7 +59,7 @@ const initialState = {
   sourceFilePath: null,
 };
 
-export const useCaptionStore = create<CaptionState>((set) => ({
+export const useCaptionStore = create<CaptionState>((set, get) => ({
   ...initialState,
 
   // Basic
@@ -82,15 +82,11 @@ export const useCaptionStore = create<CaptionState>((set) => ({
       return { selectedSegmentIds: new Set([id]), selectedGroupId: null };
     }),
 
-  selectGroup: (id) =>
-    set((state) => {
-      const group = state.model?.groups.get(id);
-      if (!group) return {};
-      return {
-        selectedSegmentIds: new Set(group.segmentIds),
-        selectedGroupId: id,
-      };
-    }),
+  selectGroup: (id) => {
+    const group = get().model?.groups.get(id);
+    if (!group) return;
+    set({ selectedSegmentIds: new Set(group.segmentIds), selectedGroupId: id });
+  },
 
   selectAll: () =>
     set((state) => {
@@ -101,7 +97,11 @@ export const useCaptionStore = create<CaptionState>((set) => ({
       };
     }),
 
-  clearSelection: () => set({ selectedSegmentIds: new Set(), selectedGroupId: null }),
+  clearSelection: () => {
+    const { selectedSegmentIds, selectedGroupId } = get();
+    if (selectedSegmentIds.size === 0 && selectedGroupId === null) return;
+    set({ selectedSegmentIds: new Set(), selectedGroupId: null });
+  },
 
   // Segment mutations
   updateSegmentStyle: (segmentId, style) =>