fix: 修复 Chrome 上录音按钮被 pointerleave 过早中断的问题

- 在 pointerdown 时调用 setPointerCapture 锁定指针事件
- 在 pointerup 时释放 pointer capture
- 防止 async startRecording 期间 pointerleave 意外触发 stopRecording
- mic-wrapper 添加 touch-action: none 防止浏览器拦截触摸

web/app.ts

@@ -359,10 +359,13 @@ function bindMicButton(): void {
 	micBtn.addEventListener("pointerdown", (e: PointerEvent) => {
 		if (e.button !== 0) return;
 		e.preventDefault();
+		// Capture pointer so pointerleave won't fire while held
+		micBtn.setPointerCapture(e.pointerId);
 		startRecording();
 	});
 	micBtn.addEventListener("pointerup", (e: PointerEvent) => {
 		e.preventDefault();
+		micBtn.releasePointerCapture(e.pointerId);
 		stopRecording();
 	});
 	micBtn.addEventListener("pointerleave", () => {

web/style.css

@@ -198,6 +198,7 @@ header h1 {
 	display: flex;
 	align-items: center;
 	justify-content: center;
+	touch-action: none;
 }
 
 #mic-btn {