refactor: move version history dropdown from AIPanel to toolbar

editor/components/AIPanel.vue

@@ -99,12 +99,6 @@ onMounted(() => {
             </button>
             <button class="ai-new-btn" @click="newSession" title="新建对话">+</button>
             <button v-if="store.aiChanges" class="ai-clear-btn" @click="store.clearAIMarkers()">清除高亮</button>
-            <select v-if="store.versions.length > 0" class="ai-version-select" @change="store.restoreVersion(($event.target as HTMLSelectElement).selectedIndex)">
-              <option disabled selected>版本</option>
-              <option v-for="v in store.versions" :key="v.timestamp">
-                {{ new Date(v.timestamp).toLocaleString('zh-CN') }} {{ v.label }}
-              </option>
-            </select>
             <button class="ai-collapse-btn" @click="store.aiCollapsed = true">▼ 折叠</button>
           </div>
         </div>
@@ -261,17 +255,6 @@ onMounted(() => {
 }
 .ai-clear-btn:hover { color: #fff; border-color: rgba(255,255,255,0.2); }
 
-.ai-version-select {
-  padding: 3px 6px;
-  font-size: 11px;
-  max-width: 90px;
-  background: rgba(255,255,255,0.05);
-  border: 1px solid rgba(255,255,255,0.1);
-  border-radius: 3px;
-  color: #ccc;
-  outline: none;
-}
-
 .ai-collapse-btn {
   padding: 3px 8px;
   font-size: 11px;