feat: Setup Wizard for first-run configuration

Container starts with only DB credentials. On first visit, a step-by-step
wizard guides through admin password, weather, HA, Vikunja, Unraid, MQTT,
n8n and news configuration. Backward-compat: ADMIN_PASSWORD env skips wizard.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/services/test_connections.py

@@ -136,6 +136,27 @@ async def test_news_db(config: Dict[str, Any]) -> Dict[str, Any]:
         return {"success": False, "message": str(exc)}
 
 
+async def test_n8n(config: Dict[str, Any]) -> Dict[str, Any]:
+    """Test n8n connection by fetching workflows."""
+    url = config.get("url", "")
+    api_key = config.get("api_key", "")
+    if not url or not api_key:
+        return {"success": False, "message": "URL und API Key sind erforderlich"}
+    try:
+        base = url.rstrip("/")
+        async with httpx.AsyncClient(timeout=TIMEOUT) as client:
+            r = await client.get(
+                f"{base}/api/v1/workflows",
+                headers={"X-N8N-API-KEY": api_key},
+            )
+            r.raise_for_status()
+            data = r.json()
+            count = len(data.get("data", []))
+            return {"success": True, "message": f"Verbunden — {count} Workflows gefunden"}
+    except Exception as exc:
+        return {"success": False, "message": str(exc)}
+
+
 # Map integration type → test function
 TEST_FUNCTIONS = {
     "weather": test_weather,
@@ -144,4 +165,5 @@ TEST_FUNCTIONS = {
     "unraid": test_unraid,
     "mqtt": test_mqtt,
     "news": test_news_db,
+    "n8n": test_n8n,
 }