feat: 品牌替换 + 启动优化 + AGENTS.md 模板定制

- 品牌替换：OpenCode/opencode → AirCoding/aircoding（16+ 文件）
- Logo ASCII art：修复 left/right 行数不匹配导致的启动崩溃
- 启动诊断：添加 OPENCODE_PRINT_TIMING 计时探针
- dev 模式默认 --pure 跳过外部插件加载
- AGENTS.md 模板：追加 AirCoding 多 Agent 专项段落
- architect prompt + plugin：强化 AGENTS.md 产出验证

packages/app/happydom.ts

@@ -0,0 +1,75 @@
+import { GlobalRegistrator } from "@happy-dom/global-registrator"
+
+GlobalRegistrator.register()
+
+const originalGetContext = HTMLCanvasElement.prototype.getContext
+// @ts-expect-error - we're overriding with a simplified mock
+HTMLCanvasElement.prototype.getContext = function (contextType: string, _options?: unknown) {
+  if (contextType === "2d") {
+    return {
+      canvas: this,
+      fillStyle: "#000000",
+      strokeStyle: "#000000",
+      font: "12px monospace",
+      textAlign: "start",
+      textBaseline: "alphabetic",
+      globalAlpha: 1,
+      globalCompositeOperation: "source-over",
+      imageSmoothingEnabled: true,
+      lineWidth: 1,
+      lineCap: "butt",
+      lineJoin: "miter",
+      miterLimit: 10,
+      shadowBlur: 0,
+      shadowColor: "rgba(0, 0, 0, 0)",
+      shadowOffsetX: 0,
+      shadowOffsetY: 0,
+      fillRect: () => {},
+      strokeRect: () => {},
+      clearRect: () => {},
+      fillText: () => {},
+      strokeText: () => {},
+      measureText: (text: string) => ({ width: text.length * 8 }),
+      drawImage: () => {},
+      save: () => {},
+      restore: () => {},
+      scale: () => {},
+      rotate: () => {},
+      translate: () => {},
+      transform: () => {},
+      setTransform: () => {},
+      resetTransform: () => {},
+      createLinearGradient: () => ({ addColorStop: () => {} }),
+      createRadialGradient: () => ({ addColorStop: () => {} }),
+      createPattern: () => null,
+      beginPath: () => {},
+      closePath: () => {},
+      moveTo: () => {},
+      lineTo: () => {},
+      bezierCurveTo: () => {},
+      quadraticCurveTo: () => {},
+      arc: () => {},
+      arcTo: () => {},
+      ellipse: () => {},
+      rect: () => {},
+      fill: () => {},
+      stroke: () => {},
+      clip: () => {},
+      isPointInPath: () => false,
+      isPointInStroke: () => false,
+      getTransform: () => ({}),
+      getImageData: () => ({
+        data: new Uint8ClampedArray(0),
+        width: 0,
+        height: 0,
+      }),
+      putImageData: () => {},
+      createImageData: () => ({
+        data: new Uint8ClampedArray(0),
+        width: 0,
+        height: 0,
+      }),
+    } as unknown as CanvasRenderingContext2D
+  }
+  return originalGetContext.call(this, contextType as "2d", _options)
+}