优化页面交互并增强 Provider 配置能力

- 表单下拉框不再用 label 包裹，改为 div + aria-label，避免点击后
  下拉面板瞬间关闭
- Provider 卡片新增「从上游获取模型」和「修改」入口，支持编辑
  base URL、API Key 与 api_mode，凭据写入对应的环境变量
- 服务端抽出 provider-model-discovery 统一不同 api_mode 的模型发现，
  旧的 custom_providers 与新的 providers 字典结构都能正确更新
- Agent Bridge 改为后台启动，HTTP 接口在 Python 运行时就绪前即可用；
  worker 连接被拒时按类型重试，不重放可能已产生副作用的请求
- 断线重连后恢复 profiles、models 与会话列表，健康检查改为自调度
  的 setTimeout，离线时 2 秒后重试
- 批量删除确认文案改用 Popconfirm content，避免变成侧栏触发器文本

packages/client/src/stores/hermes/app.ts

@@ -41,7 +41,8 @@ export const useAppStore = defineStore('app', () => {
   const customModels = ref<Record<string, string[]>>({})
   const modelAliases = ref<Record<string, Record<string, string>>>({})
   const modelVisibility = ref<ModelVisibility>({})
-  const healthPollTimer = ref<ReturnType<typeof setInterval>>()
+  const healthPollTimer = ref<ReturnType<typeof setTimeout>>()
+  let healthPollGeneration = 0
   const nodeVersion = ref('')
   const isDocker = ref(false)
 
@@ -301,13 +302,19 @@ export const useAppStore = defineStore('app', () => {
 
   function startHealthPolling(interval = 30000) {
     stopHealthPolling()
-    checkConnection()
-    healthPollTimer.value = setInterval(checkConnection, interval)
+    const generation = healthPollGeneration
+    const poll = async () => {
+      await checkConnection()
+      if (generation !== healthPollGeneration) return
+      healthPollTimer.value = setTimeout(poll, connected.value ? interval : Math.min(interval, 2000))
+    }
+    void poll()
   }
 
   function stopHealthPolling() {
+    healthPollGeneration++
     if (healthPollTimer.value) {
-      clearInterval(healthPollTimer.value)
+      clearTimeout(healthPollTimer.value)
       healthPollTimer.value = undefined
     }
   }

packages/client/src/stores/hermes/chat.ts

@@ -995,11 +995,13 @@ export const useChatStore = defineStore('chat', () => {
       } else {
         clearActiveSession()
       }
+      sessionsLoaded.value = true
+      return true
     } catch (err) {
       console.error('Failed to load sessions:', err)
+      return false
     } finally {
       isLoadingSessions.value = false
-      sessionsLoaded.value = true
     }
   }