feat(录音): RecordingOverlay 录音浮层(波形/上滑取消/太短,触摸穿透)

新增 entry/src/main/ets/components/RecordingOverlay.ets：
- @Prop state: 'recording'|'cancel'|'tooShort' 三态展示
- recording 状态：7根波形柱 setInterval(120ms) 随机高度跳动动画
- cancel 状态：红底(#C0392B) + '✕'
- tooShort 状态：暗底 + '!'
- hitTestBehavior(HitTestMode.None) 触摸穿透到下方 Web，由容器 Web.onTouch 感知手势
- aboutToAppear/aboutToDisappear 正确管理 timer 生命周期

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

entry/src/main/ets/components/RecordingOverlay.ets

@@ -0,0 +1,75 @@
+/**
+ * 录音浮层（设计 §10，纯展示，仿微信"按住说话"）。状态由容器手势驱动，自身不处理触摸
+ * （HitTestMode.None 让触摸穿透到下方 Web，由 Web.onTouch 观察手势）。
+ *  - recording：跳动波形 + "手指上滑，取消发送"
+ *  - cancel：红底 + "✕" + "松开手指，取消发送"
+ *  - tooShort：黑底 + "!" + "说话时间太短"
+ */
+@Component
+export struct RecordingOverlay {
+  /** 'recording' | 'cancel' | 'tooShort' */
+  @Prop state: string;
+  @State private bars: number[] = [0.4, 0.7, 0.5, 0.9, 0.6, 0.8, 0.45];
+  private timer: number = -1;
+
+  aboutToAppear(): void {
+    this.timer = setInterval(() => {
+      this.bars = this.bars.map(() => 0.25 + 0.75 * Math.random());
+    }, 120);
+  }
+
+  aboutToDisappear(): void {
+    if (this.timer >= 0) {
+      clearInterval(this.timer);
+      this.timer = -1;
+    }
+  }
+
+  private hintText(): string {
+    if (this.state === 'cancel') {
+      return '松开手指，取消发送';
+    }
+    if (this.state === 'tooShort') {
+      return '说话时间太短';
+    }
+    return '手指上滑，取消发送';
+  }
+
+  build() {
+    Column() {
+      Column({ space: 14 }) {
+        if (this.state === 'recording') {
+          Row({ space: 4 }) {
+            ForEach(this.bars, (h: number, i: number) => {
+              Column()
+                .width(5)
+                .height(48 * h)
+                .borderRadius(3)
+                .backgroundColor('#FFFFFF')
+            }, (h: number, i: number) => i.toString())
+          }
+          .height(52)
+          .alignItems(VerticalAlign.Center)
+        } else {
+          Text(this.state === 'cancel' ? '✕' : '!')
+            .fontSize(42)
+            .fontWeight(FontWeight.Bold)
+            .fontColor('#FFFFFF')
+        }
+        Text(this.hintText())
+          .fontSize(14)
+          .fontColor('#FFFFFF')
+      }
+      .width(168)
+      .height(168)
+      .justifyContent(FlexAlign.Center)
+      .borderRadius(18)
+      .backgroundColor(this.state === 'cancel' ? '#C0392B' : 'rgba(0, 0, 0, 0.78)')
+    }
+    .width('100%')
+    .height('100%')
+    .justifyContent(FlexAlign.Center)
+    .alignItems(HorizontalAlign.Center)
+    .hitTestBehavior(HitTestMode.None)
+  }
+}