Add streaming support and refactor Chat UI

- Add run_stream method to AgentCore for streaming output
- Add base_url parameter to LLM clients for OpenRouter support
- Add xbot module for new agent implementation
- Refactor Chat.vue into composable + components (ChatHeader, ChatMessage, ChatInput, ChatSidebar, ChatAgentSelector)
- Add ChatStream handler for SSE streaming in Go server
- Add UseXBot field to chat request

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

web/src/views/Agents.vue

@@ -19,8 +19,15 @@ const newAgent = ref({
   skills: '',
   knowledge: '',
   prompt: '',
+  avatar: '🤖',
 })
 
+// 头像选项
+const avatarOptions = [
+  '🤖', '🧠', '💻', '📊', '🔬', '🎧', '✨', '💬', '🔮', '🌙',
+  '🐉', '☁️', '🎨', '🎯', '🚀', '⚡', '🔥', '💡', '🎭', '🎪'
+]
+
 // Skills 选项
 const skillsOptions = [
   { value: 'research', label: 'Research' },
@@ -41,7 +48,7 @@ const knowledgeOptions = [
 
 // 打开创建弹窗
 const openCreateModal = () => {
-  newAgent.value = { name: '', description: '', skills: '', knowledge: '', prompt: '' }
+  newAgent.value = { name: '', description: '', skills: '', knowledge: '', prompt: '', avatar: '🤖' }
   showCreateModal.value = true
 }
 
@@ -58,7 +65,7 @@ const createAgent = async () => {
     agents.value.unshift({
       id: newId,
       name: newAgent.value.name,
-      avatar: '🤖',
+      avatar: newAgent.value.avatar,
       description: newAgent.value.description,
       accentColor: '#f97316',
       gradient: 'from-orange-500/20 to-amber-500/20',
@@ -259,6 +266,22 @@ const deleteAgent = (id: number) => {
             ></textarea>
           </div>
 
+          <div>
+            <label class="block text-sm font-medium text-gray-300 mb-2">Avatar</label>
+            <div class="flex flex-wrap gap-2">
+              <button
+                v-for="avatar in avatarOptions"
+                :key="avatar"
+                type="button"
+                @click="newAgent.avatar = avatar"
+                class="w-10 h-10 rounded-lg flex items-center justify-center text-lg transition-all"
+                :class="newAgent.avatar === avatar ? 'bg-primary-orange text-white ring-2 ring-orange-400' : 'bg-dark-600 text-gray-300 hover:bg-dark-500'"
+              >
+                {{ avatar }}
+              </button>
+            </div>
+          </div>
+
           <div>
             <label class="block text-sm font-medium text-gray-300 mb-2">Skills *</label>
             <el-select v-model="newAgent.skills" placeholder="Select skills" class="w-full" size="large" popper-class="dark-select-dropdown">