fix: 语音输出改为边生成边播报，不再等整段答案完成

TtsPlayer 本来就实现了完整的流式播报能力（append() 按句子边界切分
入队、flush() 收尾剩余文本），只是 ChatPanel 一直没接上，只在
querying 结束后调用一次 speakWithAnnouncement(全文)。

改为在 onDelta 里实时 append(delta)，onDone/onError 里 flush()
收尾。删除了原来 querying 结束时整段朗读的 watch（不删会导致
整段答案被朗读两遍）。效果：不用等生成完，第一句话生成出来就
开始播，播放速度跟不上文字输出时 TtsPlayer 自带的自适应语速会
自动降速跟上。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/renderer/src/components/ChatPanel.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref, computed, onMounted, onUnmounted, nextTick, watch } from 'vue'
+import { ref, computed, onMounted, onUnmounted, nextTick } from 'vue'
 import { NModal, NCard, NScrollbar, useMessage } from 'naive-ui'
 import { marked } from 'marked'
 import { useRagStore } from '../stores/rag'
@@ -199,13 +199,16 @@ async function sendQuery(): Promise<void> {
   const onContext = (data: unknown) => { store.chunks = (data as { chunks: Chunk[] }).chunks }
   const onDelta = (data: unknown) => {
     if (firstDelta) { firstDelta = false; stopWaitTimer() }
-    store.rawAnswer += (data as { delta: string }).delta
+    const delta = (data as { delta: string }).delta
+    store.rawAnswer += delta
+    if (ttsEnabled.value) ttsPlayer.append(delta)
     scrollToBottom()
   }
   const onDone = (data: unknown) => {
     stopWaitTimer()
     store.querying = false
     queryStage.value = ''
+    if (ttsEnabled.value) ttsPlayer.flush()
     const stats = (data as { stats?: InferStats | null }).stats
     if (stats) inferStats.value = stats
     cleanup()
@@ -214,6 +217,7 @@ async function sendQuery(): Promise<void> {
     stopWaitTimer()
     store.querying = false
     queryStage.value = ''
+    if (ttsEnabled.value) ttsPlayer.flush()
     message.error((data as { message: string }).message)
     cleanup()
   }
@@ -255,13 +259,16 @@ async function sendVisionQuery(): Promise<void> {
 
   const onDelta = (data: unknown) => {
     if (firstDelta) { firstDelta = false; stopWaitTimer() }
-    store.rawAnswer += (data as { delta: string }).delta
+    const delta = (data as { delta: string }).delta
+    store.rawAnswer += delta
+    if (ttsEnabled.value) ttsPlayer.append(delta)
     scrollToBottom()
   }
   const onDone = (data: unknown) => {
     stopWaitTimer()
     store.querying = false
     queryStage.value = ''
+    if (ttsEnabled.value) ttsPlayer.flush()
     const stats = (data as { stats?: InferStats | null }).stats
     if (stats) inferStats.value = stats
     cleanup()
@@ -270,6 +277,7 @@ async function sendVisionQuery(): Promise<void> {
     stopWaitTimer()
     store.querying = false
     queryStage.value = ''
+    if (ttsEnabled.value) ttsPlayer.flush()
     message.error((data as { message: string }).message)
     cleanup()
   }
@@ -545,13 +553,6 @@ onMounted(() => {
   }
 })
 
-watch(() => store.querying, (querying) => {
-  // 答案流式生成结束后，整段朗读（先播"开始播报"）
-  if (!querying && ttsEnabled.value && store.rawAnswer) {
-    ttsPlayer.speakWithAnnouncement(store.rawAnswer)
-  }
-})
-
 onUnmounted(() => {
   stopWaitTimer()
   if (hoverTimer) clearTimeout(hoverTimer)