fix: toten Overpass-Fallback ersetzen + Retry bei 504

- kumi.systems Fallback (tot) durch z.overpass-api.de ersetzt
- Retry-Logik bei transienten HTTP-Fehlern (502/504/429)
- 2s Pause vor Retry, dann naechster Endpunkt

src/data_overpass.py

@@ -1,6 +1,7 @@
 """Overpass Turbo: OverpassQL-Queries gegen OpenStreetMap ausfuehren."""
 import logging
 import time
+import asyncio
 import hashlib
 import httpx
 from fastapi import APIRouter, HTTPException
@@ -19,10 +20,13 @@ _CACHE_TTL = 300  # 5 Minuten
 _MAX_CACHE_ENTRIES = 50
 
 # --- Overpass API ---
-_OVERPASS_URL = "https://overpass-api.de/api/interpreter"
-_OVERPASS_FALLBACK = "https://overpass.kumi.systems/api/interpreter"
+_OVERPASS_URLS = [
+    "https://overpass-api.de/api/interpreter",
+    "https://z.overpass-api.de/api/interpreter",
+]
 _MAX_ELEMENTS = 5000
 _TIMEOUT = 60
+_RETRY_CODES = {502, 504, 429}  # Transiente Fehler
 
 
 class OverpassRequest(BaseModel):
@@ -370,20 +374,30 @@ async def execute_query(req: OverpassRequest):
 
     _last_request_time = time.time()
 
-    # Query ausfuehren
+    # Query ausfuehren (mit Retry bei transienten Fehlern)
     data = None
-    for url in [_OVERPASS_URL, _OVERPASS_FALLBACK]:
+    last_error = None
+    for url in _OVERPASS_URLS:
+        for attempt in range(2):
             try:
                 async with httpx.AsyncClient(timeout=_TIMEOUT) as client:
                     r = await client.post(url, data={"data": query})
+                    if r.status_code in _RETRY_CODES and attempt == 0:
+                        logger.info(f"Overpass {url}: {r.status_code}, retry in 2s...")
+                        await asyncio.sleep(2)
+                        continue
                     r.raise_for_status()
                     data = r.json()
                     break
             except Exception as e:
-            logger.warning(f"Overpass {url}: {e}")
-            continue
+                last_error = f"{url}: {e}"
+                logger.warning(f"Overpass {url} (attempt {attempt+1}): {e}")
+                break
+        if data is not None:
+            break
 
     if data is None:
+        logger.error(f"Alle Overpass-Endpunkte fehlgeschlagen: {last_error}")
         raise HTTPException(502, "Overpass API nicht erreichbar")
 
     elements = data.get("elements", [])