Refactor: TanStack-Query-Daten-Layer + useDialog (Phase 3b)

- @tanstack/react-query (v5) als zentraler Daten-Layer; QueryClientProvider
  in main.tsx (retry 1, kein refetchOnWindowFocus, staleTime 5s).
- lib/queries.ts: Domänen-Hooks (useHealth/useSystemStatus/useServices/
  useModels/useRouting/useJobs/useTokenStats/useAgentStatus/useUpdates/
  useDiscover/useConnect/useMemory) + zentrale Query-Keys (qk) + invalidate.
  Gleicher Key = eine Anfrage über alle Views (Dedup), einheitliches Polling.
- lib/useDialog.tsx: ein Hook für Alert/Confirm/Prompt statt 5x dupliziertem
  Dialog-State + showAlert/showConfirm.
- api.ts: TokenStats + ModelsResp typisiert.
- Migriert auf Hooks/useDialog: App, SystemView, AgentView, ConnectView,
  MemoryView (manuelles useEffect+setInterval entfernt; Mutationen
  invalidieren gezielt die Query-Keys).

Verifiziert: tsc grün, Build grün, alle migrierten Views ohne Konsolenfehler,
Live-Daten (CPU/RAM/Dienste) rendern korrekt.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/views/ConnectView.tsx

@@ -1,24 +1,18 @@
-import { useEffect, useState } from "react"
+import { useState } from "react"
 import { Check, Copy, Terminal, Info, Globe, FolderOpen } from "lucide-react"
-import { api, type ConnectResp } from "@/lib/api"
+import { useConnect } from "@/lib/queries"
 import { cn } from "@/lib/utils"
 
 export function ConnectView() {
   const [host, setHost] = useState(localStorage.getItem("mc_host") || "192.168.178.151")
   const [mcpPath, setMcpPath] = useState(localStorage.getItem("mc_mcp_path") || "")
-  const [data, setData] = useState<ConnectResp | null>(null)
   const [active, setActive] = useState("cline")
   const [copied, setCopied] = useState(false)
-  const [error, setError] = useState("")
 
-  useEffect(() => {
-    const params = new URLSearchParams()
-    params.set("host", host)
-    if (mcpPath) params.set("mcp_path", mcpPath)
-    api<ConnectResp>(`/api/connect?${params}`)
-      .then(setData)
-      .catch((e) => setError(String(e)))
-  }, [host, mcpPath])
+  const params = new URLSearchParams({ host })
+  if (mcpPath) params.set("mcp_path", mcpPath)
+  const { data, error: dataErr } = useConnect(params.toString())
+  const error = dataErr ? String(dataErr) : ""
 
   function saveHost(v: string) {
     setHost(v)