Feature: Börsenstrompreis-Chart (EPEX SPOT via aWATTar) im Energie-Dashboard (v1.8.0)

- /api/spot-price: Proxy zu api.awattar.de/v1/marketdata, 15-min Cache
- EUR/MWh → ct/kWh Konvertierung
- SVG-Balkenchart 24h-Prognose, gleiche Breite wie Flussdiagramm (viewBox 520)
- Farbe nach Preistertil: grün/gelb/rot; aktuelle Stunde hervorgehoben
- Aktuellen Preis als ct/kWh-Label in der Kopfzeile

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

haos-addon/src/main.py

@@ -545,6 +545,29 @@ def api_import_config():
     threading.Thread(target=_restart_all, daemon=True).start()
     return jsonify({"ok": True, "inverters": len(inverters)})
 
+_spot_cache: Dict[str, Any] = {"ts": 0.0, "data": []}
+_SPOT_TTL = 900  # 15 Minuten
+
+@app.get("/api/spot-price")
+def api_spot_price():
+    import urllib.request as _ur
+    global _spot_cache
+    now = time.time()
+    if now - _spot_cache["ts"] < _SPOT_TTL and _spot_cache["data"]:
+        return jsonify({"ok": True, "data": _spot_cache["data"]})
+    try:
+        with _ur.urlopen("https://api.awattar.de/v1/marketdata", timeout=8) as r:
+            raw = json.loads(r.read())
+        entries = [
+            {"ts": int(d["start_timestamp"] // 1000), "price": round(d["marketprice"] / 10, 2)}
+            for d in raw.get("data", [])
+        ]
+        _spot_cache = {"ts": now, "data": entries}
+        return jsonify({"ok": True, "data": entries})
+    except Exception as e:
+        log.warning("Spot-Price API Fehler: %s", e)
+        return jsonify({"ok": False, "data": _spot_cache.get("data", [])})
+
 @app.get("/")
 def index():
     return send_from_directory(WEB_DIR, "index.html")