feat: add WLED device status check (online/offline, LEDs, version)

- Query WLED JSON API (/json/info) for device info
- Show online/offline status dot, LED count and firmware version
- Auto-check all devices on page load
- Button to manually check individual or all devices
- Fix hostname placeholder to volksheimstaette.de

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

wled_client.py

@@ -24,3 +24,24 @@ def call_wled(url):
     except requests.exceptions.RequestException as e:
         logger.warning("WLED nicht erreichbar: %s - %s", url, e)
         return False, str(e)
+
+
+def get_wled_info(hostname):
+    """Query WLED JSON API for device info. Returns dict or None."""
+    try:
+        r = requests.get(f"http://{hostname}/json/info", timeout=TIMEOUT)
+        if r.status_code == 200:
+            data = r.json()
+            return {
+                "online": True,
+                "name": data.get("name", ""),
+                "version": data.get("ver", ""),
+                "brand": data.get("brand", "WLED"),
+                "mac": data.get("mac", ""),
+                "ip": data.get("ip", ""),
+                "leds": data.get("leds", {}).get("count", 0),
+                "power_on": data.get("state", {}).get("on", False) if "state" not in data else None,
+            }
+        return {"online": False}
+    except requests.exceptions.RequestException:
+        return {"online": False}