feat(sticky): add StickySprite renderer

frontend/src/canvas/sprites/StickySprite.ts

@@ -0,0 +1,115 @@
+/**
+ * StickySprite — renders a sticky note card.
+ *
+ * Structure:
+ *   Container (this)
+ *     └─ _bg: Graphics (rounded rect background)
+ *     └─ _text: Text (word-wrapped content)
+ *
+ * Dimensions:
+ *   - width is fixed (from data.w)
+ *   - height auto-grows to fit wrapped text + padding
+ *   - parent SceneItem.data.h is updated after layout
+ */
+
+import { Container, Graphics, Text, TextStyle } from 'pixi.js';
+import type { StickyObject } from '../scene-format';
+
+const DEFAULT_PADDING = 16;
+const DEFAULT_CORNER_RADIUS = 8;
+const DEFAULT_LINE_HEIGHT = 1.4;
+const MIN_HEIGHT = 60;
+
+export class StickySprite extends Container {
+  private _bg: Graphics;
+  private _text: Text;
+  private _style: TextStyle;
+
+  // Cached layout state
+  private _cardW = 200;
+  private _cardH = MIN_HEIGHT;
+  private _padding = DEFAULT_PADDING;
+  private _cornerRadius = DEFAULT_CORNER_RADIUS;
+  private _bgColor = '#ffd43b';
+
+  /** After layout, the computed card height. Parent should sync to data.h. */
+  get computedHeight(): number {
+    return this._cardH;
+  }
+
+  /** Show/hide the text child (used by TextEditor during editing). */
+  showText(visible: boolean): void {
+    this._text.visible = visible;
+  }
+
+  constructor(data: StickyObject) {
+    super();
+
+    this._padding = data.padding ?? DEFAULT_PADDING;
+    this._cornerRadius = data.cornerRadius ?? DEFAULT_CORNER_RADIUS;
+    this._bgColor = data.fill || '#ffd43b';
+    this._cardW = data.w;
+
+    // Background
+    this._bg = new Graphics();
+    this.addChild(this._bg);
+
+    // Text style
+    this._style = new TextStyle({
+      fontSize: data.fontSize || 14,
+      fontFamily: data.fontFamily || 'Inter, system-ui, sans-serif',
+      fill: data.textColor || '#1a1a1a',
+      wordWrap: true,
+      wordWrapWidth: Math.max(data.w - this._padding * 2, 1),
+      lineHeight: (data.fontSize || 14) * DEFAULT_LINE_HEIGHT,
+    });
+
+    this._text = new Text({ text: data.text || '', style: this._style });
+    this._text.position.set(this._padding, this._padding);
+    this.addChild(this._text);
+
+    this._layout();
+  }
+
+  /**
+   * Update from StickyObject data. Called by SceneManager._updateItem().
+   */
+  updateFromData(data: StickyObject): void {
+    this._padding = data.padding ?? DEFAULT_PADDING;
+    this._cornerRadius = data.cornerRadius ?? DEFAULT_CORNER_RADIUS;
+    this._bgColor = data.fill || '#ffd43b';
+    this._cardW = data.w;
+
+    // Update text content and style
+    this._text.text = data.text || '';
+    this._style.fontSize = data.fontSize || 14;
+    this._style.fontFamily = data.fontFamily || 'Inter, system-ui, sans-serif';
+    this._style.fill = data.textColor || '#1a1a1a';
+    this._style.wordWrapWidth = Math.max(data.w - this._padding * 2, 1);
+    this._style.lineHeight = (data.fontSize || 14) * DEFAULT_LINE_HEIGHT;
+    this._text.style = this._style;
+
+    this._text.position.set(this._padding, this._padding);
+    this._layout();
+  }
+
+  /**
+   * Recompute layout: measure text height, resize card, redraw background.
+   * Returns the new card height so the caller can sync data.h.
+   */
+  private _layout(): void {
+    // Measure the PixiJS text after style update
+    const textBounds = this._text.getLocalBounds();
+    const textH = textBounds.height;
+
+    // Card height: text + top/bottom padding, minimum height
+    this._cardH = Math.max(textH + this._padding * 2, MIN_HEIGHT);
+
+    // Redraw background
+    this._bg.clear();
+    const color = parseInt(this._bgColor.replace('#', ''), 16) || 0xffd43b;
+    this._bg.roundRect(0, 0, this._cardW, this._cardH, this._cornerRadius);
+    this._bg.fill({ color, alpha: 1 });
+    this._bg.stroke({ color: 0x000000, alpha: 0.1, width: 1 });
+  }
+}