fix(ui): Phase 19 P1 修復 Header「已斷線」狀態

問題: 非 Dashboard 頁面顯示「已斷線」，因為 SSE 只在 Dashboard 啟動

修復:
- AppLayout 全局啟動 SSE 連接 (所有頁面共享)
- LiveDashboard 移除重複的 SSE 連接邏輯
- 現在所有頁面都會顯示正確的連線狀態

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/src/components/dashboard/live-dashboard.tsx

@@ -61,7 +61,8 @@ export function LiveDashboard({ locale }: LiveDashboardProps) {
   const tBrand = useTranslations('brand')
   const tHost = useTranslations('host')
 
-  const { connect, disconnect } = useDashboardStore()
+  // Phase 19 修復: SSE 連接已移至 AppLayout 全局管理
+  // const { connect, disconnect } = useDashboardStore()
   const hosts = useHosts()
   const overallStatus = useOverallStatus()
   const alerts = useAlerts()
@@ -110,16 +111,12 @@ export function LiveDashboard({ locale }: LiveDashboardProps) {
     },
   }
 
-  useEffect(() => {
-    const apiBaseUrl = getApiBaseUrl()
-    console.log('[Dashboard] Connecting to SSE...', apiBaseUrl)
-    connect(apiBaseUrl)
-
-    return () => {
-      console.log('[Dashboard] Disconnecting SSE...')
-      disconnect()
-    }
-  }, [connect, disconnect])
+  // Phase 19 修復: SSE 連接已移至 AppLayout 全局管理
+  // useEffect(() => {
+  //   const apiBaseUrl = getApiBaseUrl()
+  //   connect(apiBaseUrl)
+  //   return () => disconnect()
+  // }, [connect, disconnect])
 
   return (
     <div className="space-y-6">

apps/web/src/components/layout/app-layout.tsx

@@ -9,6 +9,9 @@
  * - 響應式側邊欄折疊
  * - 主內容區域自動適應
  * - 持久化折疊狀態 (localStorage)
+ * - **Phase 19 修復**: 全局 SSE 連接 (所有頁面共享連線狀態)
+ *
+ * @updated 2026-03-28 - 修復 Header「已斷線」狀態問題
  */
 
 import { useState, useEffect } from 'react'
@@ -16,6 +19,7 @@ import { Sidebar } from './sidebar'
 import { Header } from './header'
 import { DotMatrixBg } from '@/components/ui/dot-matrix-bg'
 import { cn } from '@/lib/utils'
+import { useDashboardStore } from '@/stores/dashboard.store'
 
 // =============================================================================
 // Types
@@ -45,6 +49,9 @@ export function AppLayout({
   const [collapsed, setCollapsed] = useState(false)
   const [mounted, setMounted] = useState(false)
 
+  // Phase 19 修復: 全局 SSE 連接
+  const { connect, disconnect } = useDashboardStore()
+
   // Load collapsed state from localStorage
   useEffect(() => {
     setMounted(true)
@@ -54,6 +61,20 @@ export function AppLayout({
     }
   }, [])
 
+  // Phase 19 修復: 全局啟動 SSE 連接 (所有頁面共享)
+  useEffect(() => {
+    const apiBaseUrl = process.env.NEXT_PUBLIC_API_URL || ''
+    if (apiBaseUrl) {
+      console.log('[AppLayout] 全局 SSE 連接啟動...', apiBaseUrl)
+      connect(apiBaseUrl)
+    }
+
+    return () => {
+      console.log('[AppLayout] SSE 連接關閉')
+      disconnect()
+    }
+  }, [connect, disconnect])
+
   // Save collapsed state to localStorage
   const handleToggle = () => {
     const newState = !collapsed