fix: address code review findings from crop/text commit

- CropOverlay: register move/up handlers dynamically on drag start (single
  handler instead of 8x per-handle), remove on drag end. Override destroy()
  to call _cleanup() preventing keyboard listener leaks.
- Text format toolbar: re-measure text bounds (w/h) after fontSize/fontFamily
  changes, update spatial index and transform box.
- TextEditor: add clearText() method; tools.ts uses it instead of fragile
  document.querySelector('textarea').
- SceneManager._updateItem: apply crop mask on remote sync for image items.
- useCanvasSetup: stop TextEditor on unmount to prevent orphaned textarea.
- Double-click zoom: use item.data dimensions instead of getBounds() (which
  includes shadow offset).

frontend/src/canvas/CropOverlay.ts

@@ -10,7 +10,6 @@ import { Container, Graphics, FederatedPointerEvent } from 'pixi.js';
 import type { Viewport } from 'pixi-viewport';
 import type { SceneItem } from './SceneManager';
 import type { ImageObject, CropRect } from './scene-format';
-import { ImageSprite } from './sprites/ImageSprite';
 
 const HANDLE_SIZE = 8;
 const HANDLE_FILL = 0xffffff;
@@ -32,6 +31,9 @@ export class CropOverlay extends Container {
   private _onConfirm: ((item: SceneItem, crop: CropRect) => void) | null = null;
   private _onCancel: (() => void) | null = null;
   private _keyHandler: ((e: KeyboardEvent) => void) | null = null;
+  // Bound references for dynamic event registration
+  private _boundMove: ((e: FederatedPointerEvent) => void) | null = null;
+  private _boundUp: (() => void) | null = null;
 
   constructor(viewport: Viewport) {
     super();
@@ -50,7 +52,7 @@ export class CropOverlay extends Container {
     this._border.eventMode = 'none';
     this.addChild(this._border);
 
-    // Create handles
+    // Create handles — only pointerdown on each handle
     const ids: HandleId[] = ['tl', 'tc', 'tr', 'ml', 'mr', 'bl', 'bc', 'br'];
     const cursors: Record<HandleId, string> = {
       tl: 'nwse-resize', tr: 'nesw-resize', bl: 'nesw-resize', br: 'nwse-resize',
@@ -61,9 +63,6 @@ export class CropOverlay extends Container {
       h.eventMode = 'static';
       h.cursor = cursors[id];
       h.on('pointerdown', (e: FederatedPointerEvent) => this._onDown(e, id));
-      h.on('globalpointermove', (e: FederatedPointerEvent) => this._onMove(e));
-      h.on('pointerup', () => this._onUp());
-      h.on('pointerupoutside', () => this._onUp());
       this._handles.set(id, h);
       this.addChild(h);
     }
@@ -94,7 +93,6 @@ export class CropOverlay extends Container {
     if (!this._item) return;
     const item = this._item;
     const crop = { ...this._crop };
-    // If crop is full image, remove it
     const isFullImage = crop.x < 0.001 && crop.y < 0.001 && crop.w > 0.999 && crop.h > 0.999;
     this._cleanup();
     this._onConfirm?.(item, isFullImage ? { x: 0, y: 0, w: 1, h: 1 } : crop);
@@ -108,7 +106,9 @@ export class CropOverlay extends Container {
 
   get isActive(): boolean { return this._item !== null; }
 
+  /** Clean up all state and listeners. Safe to call multiple times. */
   private _cleanup(): void {
+    this._removeDragListeners();
     this._item = null;
     this._drag = null;
     this.visible = false;
@@ -118,6 +118,12 @@ export class CropOverlay extends Container {
     }
   }
 
+  /** Override destroy to ensure cleanup runs. */
+  override destroy(options?: any): void {
+    this._cleanup();
+    super.destroy(options);
+  }
+
   private _draw(): void {
     if (!this._item) return;
     const data = this._item.data;
@@ -135,26 +141,21 @@ export class CropOverlay extends Container {
     const cw = this._crop.w * iw;
     const ch = this._crop.h * ih;
 
-    // Dim: draw full image rect, then cut out the crop area using inverted mask approach
-    // Simpler: draw 4 dim rectangles around the crop area
+    // Dim: draw 4 rectangles around the crop area
     this._dim.clear();
-    // Top
     if (cy > iy) {
       this._dim.rect(ix, iy, iw, cy - iy);
       this._dim.fill({ color: 0x000000, alpha: DIM_ALPHA });
     }
-    // Bottom
     const cropBottom = cy + ch;
     if (cropBottom < iy + ih) {
       this._dim.rect(ix, cropBottom, iw, iy + ih - cropBottom);
       this._dim.fill({ color: 0x000000, alpha: DIM_ALPHA });
     }
-    // Left
     if (cx > ix) {
       this._dim.rect(ix, cy, cx - ix, ch);
       this._dim.fill({ color: 0x000000, alpha: DIM_ALPHA });
     }
-    // Right
     const cropRight = cx + cw;
     if (cropRight < ix + iw) {
       this._dim.rect(cropRight, cy, ix + iw - cropRight, ch);
@@ -201,11 +202,35 @@ export class CropOverlay extends Container {
     }
   }
 
-  // -- Handle drag --
+  // -- Handle drag (single handler, registered dynamically) --
 
   private _onDown(e: FederatedPointerEvent, id: HandleId): void {
     e.stopPropagation();
     this._drag = { handleId: id, startCrop: { ...this._crop } };
+
+    // Register move/up on the stage (single handler, not per-handle)
+    this._removeDragListeners();
+    this._boundMove = (ev: FederatedPointerEvent) => this._onMove(ev);
+    this._boundUp = () => this._onUp();
+    const stage = this._viewport.parent;
+    if (stage) {
+      stage.on('globalpointermove', this._boundMove);
+      stage.on('pointerup', this._boundUp);
+      stage.on('pointerupoutside', this._boundUp);
+    }
+  }
+
+  private _removeDragListeners(): void {
+    const stage = this._viewport.parent;
+    if (stage) {
+      if (this._boundMove) stage.off('globalpointermove', this._boundMove);
+      if (this._boundUp) {
+        stage.off('pointerup', this._boundUp);
+        stage.off('pointerupoutside', this._boundUp);
+      }
+    }
+    this._boundMove = null;
+    this._boundUp = null;
   }
 
   private _onMove(e: FederatedPointerEvent): void {
@@ -216,7 +241,6 @@ export class CropOverlay extends Container {
     const ih = data.h * data.sy;
     const world = this._viewport.toWorld(e.global.x, e.global.y);
 
-    // Convert world position to normalized image coordinates
     const nx = (world.x - data.x) / iw;
     const ny = (world.y - data.y) / ih;
 
@@ -266,5 +290,6 @@ export class CropOverlay extends Container {
 
   private _onUp(): void {
     this._drag = null;
+    this._removeDragListeners();
   }
 }