feat: Graphify build worker endpoints + UI trigger

- POST /api/aos/instances/[id]/graph-build: trigger or get build command
- POST /api/aos/instances/[id]/graph-status: worker callback (ok/error)
- GET /api/aos/graphify-health: check if Graphify service is up
- Instance detail: 'Graph neu erstellen' button (visible when demo_active/active)
- Graceful degradation: if GRAPHIFY_URL not set, returns build command for external worker

src/app/api/aos/graphify-health/route.ts

@@ -0,0 +1,32 @@
+import { NextResponse } from 'next/server'
+import { createGraphifyClientFromEnv } from '@/lib/graphify'
+
+export const dynamic = 'force-dynamic'
+
+// GET /api/aos/graphify-health
+// Checks if the Graphify MCP HTTP service is configured and reachable.
+// Used by the instance detail UI to show whether graphify is available.
+export async function GET() {
+  const url = process.env.GRAPHIFY_URL
+  if (!url) {
+    return NextResponse.json({
+      configured: false,
+      ok: false,
+      message: 'Graphify not configured (GRAPHIFY_URL missing)',
+    })
+  }
+
+  const client = createGraphifyClientFromEnv()
+  if (!client) {
+    return NextResponse.json({ configured: true, ok: false, message: 'client init failed' })
+  }
+
+  const health = await client.health()
+  return NextResponse.json({
+    configured: true,
+    ok: health.ok,
+    url,
+    version: health.version,
+    message: health.ok ? 'Graphify service is up' : 'Graphify service unreachable',
+  })
+}