fix(NodeSwitcher): move all hooks before conditional return to comply with React hooks rules

- All hooks (useState, useCallback, useEffect) must be called before any conditional return
- Add document check in updateRoleState
- Merge SSR and isMaster checks into single return at the end

web/src/components/business/NodeSwitcher.tsx

@@ -20,15 +20,6 @@ export function NodeSwitcher() {
   const [mounted, setMounted] = useState(false)
   const buttonRef = useRef<HTMLButtonElement>(null)
 
-  useEffect(() => {
-    setMounted(true)
-    // 在客户端初始化时从 localStorage 读取选中的节点
-    setSelected(activeInterconnectNodeId || 'local')
-  }, [])
-
-  // SSR 时返回 null，避免 hydration 错误
-  if (!mounted) return null
-
   const fetchNodes = useCallback(async () => {
     try {
       const res = await getNodes()
@@ -48,15 +39,23 @@ export function NodeSwitcher() {
       } else {
         setNodes([])
         setSelected('local')
-        const traveling = !!document.cookie.match(/(?:^| )active_interconnect_node_id=([^;]*)/)
-        if (activeInterconnectNodeId && !traveling) {
-          setActiveInterconnectNodeId('')
+        if (typeof document !== 'undefined') {
+          const traveling = !!document.cookie.match(/(?:^| )active_interconnect_node_id=([^;]*)/)
+          if (activeInterconnectNodeId && !traveling) {
+            setActiveInterconnectNodeId('')
+          }
         }
       }
     },
     [fetchNodes],
   )
 
+  useEffect(() => {
+    setMounted(true)
+    // 在客户端初始化时从 localStorage 读取选中的节点
+    setSelected(activeInterconnectNodeId || 'local')
+  }, [])
+
   useEffect(() => {
     ;(async () => {
       try {
@@ -85,47 +84,25 @@ export function NodeSwitcher() {
     }
   }, [isMaster, fetchNodes])
 
-  if (!isMaster) return null
-
-  const handleSelect = (val: string) => {
-    setSelected(val)
-    setOpen(false)
-    if (val === 'local') {
-      setActiveInterconnectNodeId('')
-    } else {
-      const name = nodes.find((n) => n.id === val)?.name || ''
-      setActiveInterconnectNodeId(val, name)
-    }
-    window.location.reload()
-  }
-
-  const allOptions = [
-    { value: 'local', label: '本机节点' },
-    ...nodes.map((n) => ({ value: n.id, label: n.name })),
-  ]
-
-  const currentLabel = allOptions.find((o) => o.value === selected)?.label || '本机节点'
-
-  const updateMenuPosition = () => {
-    const el = buttonRef.current
-    if (!el) return
-    const rect = el.getBoundingClientRect()
-    const viewportH = window.innerHeight
-    const spaceBelow = viewportH - rect.bottom
-    const openUp = spaceBelow < 220 && rect.top > spaceBelow
-    setMenuStyle({
-      position: 'fixed',
-      left: rect.left,
-      width: Math.max(rect.width, 140),
-      zIndex: 80,
-      ...(openUp
-        ? { bottom: viewportH - rect.top + 6, top: 'auto' }
-        : { top: rect.bottom + 6, bottom: 'auto' }),
-    })
-  }
-
   useEffect(() => {
     if (!open) return
+    const updateMenuPosition = () => {
+      const el = buttonRef.current
+      if (!el) return
+      const rect = el.getBoundingClientRect()
+      const viewportH = window.innerHeight
+      const spaceBelow = viewportH - rect.bottom
+      const openUp = spaceBelow < 220 && rect.top > spaceBelow
+      setMenuStyle({
+        position: 'fixed',
+        left: rect.left,
+        width: Math.max(rect.width, 140),
+        zIndex: 80,
+        ...(openUp
+          ? { bottom: viewportH - rect.top + 6, top: 'auto' }
+          : { top: rect.bottom + 6, bottom: 'auto' }),
+      })
+    }
     updateMenuPosition()
     const onDoc = (e: MouseEvent) => {
       const t = e.target as Node
@@ -148,6 +125,28 @@ export function NodeSwitcher() {
     }
   }, [open])
 
+  // SSR 时或非 master 节点时返回 null
+  if (!mounted || !isMaster) return null
+
+  const handleSelect = (val: string) => {
+    setSelected(val)
+    setOpen(false)
+    if (val === 'local') {
+      setActiveInterconnectNodeId('')
+    } else {
+      const name = nodes.find((n) => n.id === val)?.name || ''
+      setActiveInterconnectNodeId(val, name)
+    }
+    window.location.reload()
+  }
+
+  const allOptions = [
+    { value: 'local', label: '本机节点' },
+    ...nodes.map((n) => ({ value: n.id, label: n.name })),
+  ]
+
+  const currentLabel = allOptions.find((o) => o.value === selected)?.label || '本机节点'
+
   return (
     <div className="relative">
       <button