fix: 修复录音总是"太短"——去掉mouseleave误触+异步竞态

根因：mic按钮的scale放大动画使鼠标瞬间脱离按钮触发mouseleave，
录音刚开就被停。改为：
- window级mouseup监听（松手在哪都能停），去掉mouseleave
- pressing标志处理getUserMedia异步竞态（await期间松手则放弃/补停）
- onaudioprocess不再依赖recording标志，避免漏帧
- 呼吸动画用box-shadow代替scale

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/ai-chat/index.vue

@@ -120,12 +120,10 @@
       <!-- 麦克风按钮（同时支持触摸和鼠标，方便桌面浏览器测试） -->
       <view
         :class="['mic-btn', recording ? 'recording' : '']"
-        @touchstart.prevent="startRecord"
-        @touchend.prevent="stopRecord"
-        @touchcancel.prevent="cancelRecord"
-        @mousedown.prevent="startRecord"
-        @mouseup.prevent="stopRecord"
-        @mouseleave.prevent="onMicLeave"
+        @touchstart.prevent="onPressStart"
+        @touchend.prevent="onPressEnd"
+        @touchcancel.prevent="onPressCancel"
+        @mousedown.prevent="onMouseDown"
       >
         <text class="mic-icon">{{ recording ? '●' : '🎤' }}</text>
       </view>
@@ -175,6 +173,7 @@ export default {
       exampleTags: ['各班组查获排名', '打火机查获数量', '旅检一部人员资质', '全站党员人数'],
       // 录音相关（Web Audio 直接采集 PCM）
       recording: false,
+      pressing: false,
       recordCancelled: false,
       audioCtx: null,
       mediaStream: null,
@@ -185,14 +184,39 @@ export default {
     }
   },
   methods: {
-    // ============ 录音相关（Web Audio 直接采集原始 PCM，避免 decodeAudioData 失败）============
-    async startRecord(e) {
-      if (this.loading) return
+    // ============ 按压事件包装 ============
+    onMouseDown(e) {
+      // 鼠标：松手可能在按钮外，用 window 级监听
+      this._winUp = () => this.onPressEnd()
+      window.addEventListener('mouseup', this._winUp, { once: true })
+      this.onPressStart(e)
+    },
+    onPressStart(e) {
+      if (this.loading || this.pressing) return
+      this.pressing = true
+      this.startRecord()
+    },
+    onPressEnd(e) {
+      if (!this.pressing) return
+      this.pressing = false
+      this.stopRecord()
+    },
+    onPressCancel(e) {
+      if (!this.pressing) return
+      this.pressing = false
+      this.recordCancelled = true
+      this.stopRecord()
+    },
+
+    // ============ 录音相关（Web Audio 直接采集原始 PCM）============
+    async startRecord() {
       this.recordCancelled = false
       this.pcmChunks = []
 
       try {
         const stream = await navigator.mediaDevices.getUserMedia({ audio: true })
+        // 异步竞态：若 await 期间已松手，直接放弃
+        if (!this.pressing) { stream.getTracks().forEach(t => t.stop()); return }
         this.mediaStream = stream
 
         const AudioCtx = window.AudioContext || window.webkitAudioContext
@@ -204,8 +228,7 @@ export default {
         const source = ctx.createMediaStreamSource(stream)
         const node = ctx.createScriptProcessor(4096, 1, 1)
         node.onaudioprocess = (ev) => {
-          if (!this.recording) return
-          // 复制一份当前帧的 Float32 PCM
+          // 只要节点还连着就采集（不依赖 recording 标志，避免漏帧）
           this.pcmChunks.push(new Float32Array(ev.inputBuffer.getChannelData(0)))
         }
         source.connect(node)
@@ -214,7 +237,11 @@ export default {
         this.sourceNode = source
         this.scriptNode = node
         this.recording = true
+
+        // 若设置过程中已松手，立即停止并提交
+        if (!this.pressing) this.stopRecord()
       } catch (err) {
+        this.recording = false
         let msg = '无法访问麦克风'
         if (!navigator.mediaDevices || !navigator.mediaDevices.getUserMedia) {
           msg = '当前环境不支持录音（需HTTPS或localhost）'
@@ -238,7 +265,7 @@ export default {
       this.audioCtx = null
     },
 
-    stopRecord(e) {
+    stopRecord() {
       if (!this.recording) return
       this.recording = false
       const rate = this.pcmSampleRate
@@ -247,18 +274,6 @@ export default {
       if (!this.recordCancelled) this.submitAudio(chunks, rate)
     },
 
-    cancelRecord(e) {
-      if (!this.recording) return
-      this.recordCancelled = true
-      this.recording = false
-      this._teardownAudio()
-    },
-
-    // 鼠标移出按钮：录音中则发送（等同松手）
-    onMicLeave(e) {
-      if (this.recording) this.stopRecord(e)
-    },
-
     async submitAudio(chunks, srcRate) {
       // 合并所有 PCM 帧
       let total = 0
@@ -742,14 +757,15 @@ $text-sub: #999;
   transition: background 0.2s;
   &.recording {
     background: #ff4d4f;
-    animation: pulse 0.8s infinite;
+    animation: micPulse 0.8s infinite;
   }
 }
 .mic-icon { font-size: 32rpx; line-height: 1; }
 
-@keyframes pulse {
-  0%, 100% { transform: scale(1); }
-  50% { transform: scale(1.12); }
+/* 用阴影呼吸代替 scale，避免缩放触发 mouseleave */
+@keyframes micPulse {
+  0%, 100% { box-shadow: 0 0 0 0 rgba(255,77,79,0.5); }
+  50% { box-shadow: 0 0 0 12rpx rgba(255,77,79,0); }
 }
 
 /* 录音浮层 */