feat(2.0): Phase 0 — Greenfield-Skeleton (FastAPI + React/shadcn)

Backend: FastAPI mit /api/health + /api/models (read-only aus llama-swap
config, Logik aus v1 portiert). Frontend: Vite + React + Tailwind v4 +
shadcn-Style App-Shell mit Cmd+K, Dark-default, PWA-Manifest; Modelle-View
live aus /api/models. Deploy-Geruest (systemd-Unit :9001, build/deploy-
Skripte, NOPASSWD-sudoers, kein Klartext-Passwort).

Verifiziert: Backend-Endpunkte + Frontend-Build + gerenderte Shell.

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

frontend/src/views/Placeholder.tsx

@@ -0,0 +1,16 @@
+import { Construction } from "lucide-react"
+
+export function Placeholder({ title, hint }: { title: string; hint: string }) {
+  return (
+    <div className="space-y-4">
+      <div>
+        <h1 className="text-xl font-semibold">{title}</h1>
+        <p className="text-sm text-muted-foreground">{hint}</p>
+      </div>
+      <div className="flex flex-col items-center justify-center gap-3 rounded-xl border border-dashed border-border bg-card/50 py-20 text-center">
+        <Construction className="h-8 w-8 text-muted-foreground" />
+        <div className="text-sm text-muted-foreground">Kommt in einer späteren Phase.</div>
+      </div>
+    </div>
+  )
+}