修复 Open-Meteo 冷却期无限循环导致多模型数据缺失

- fetch_all_sources 新增 om_from_cache_only 模式：force_refresh_observations_only
  时直接从内存缓存取 OM 数据，不发起 HTTP 请求。缓存未命中则跳过，
  避免机场推送 60s 周期持续触发 429 限流
- nws_open_meteo_sources 三类 fetch 函数冷却期加磁盘缓存兜底：
  内存未命中时 force-reload SQLite 磁盘缓存再查一次
- 预热停止后冷却期自然过期（900s），下一次正常请求会填充缓存

scripts/check_city_cache.py

@@ -0,0 +1,23 @@
+"""Check which cities have hourly / multi-model data in the analysis cache."""
+import urllib.request, json
+
+TOK = "Bearer ZLuvwSsQvHSj2geIWfX7gjn9rJU_heOlgq0FBp7cUOgXaB2eHbE20R4PKwonP2FP"
+CITIES = [
+    "london", "paris", "amsterdam", "helsinki", "istanbul", "ankara",
+    "moscow", "new york", "los angeles", "chicago", "miami", "houston",
+    "lagos", "jeddah", "karachi", "tel aviv",
+]
+
+for city in CITIES:
+    url = f"http://localhost:8000/api/city/{city}/detail?force_refresh=false"
+    req = urllib.request.Request(url, headers={"Authorization": TOK})
+    try:
+        r = urllib.request.urlopen(req, timeout=30)
+        d = json.loads(r.read())
+    except Exception as e:
+        print(f"{city}: FAILED {e}")
+        continue
+    h = d.get("timeseries", {}).get("hourly", {})
+    m = d.get("models", {})
+    deb = d.get("deb", {})
+    print(f"{city}: hourly={len(h.get('times',[]))}p models={len(m)} deb={deb.get('prediction')}")

scripts/check_om_cache.py

@@ -0,0 +1,14 @@
+"""Check which cities have Open-Meteo cache entries in the web container."""
+import time
+from src.data_collection.weather_sources import WeatherDataCollector
+from src.utils.config_loader import load_config
+
+w = WeatherDataCollector(load_config())
+print("Multi-model cache entries:")
+for k in sorted(w._multi_model_cache.keys()):
+    age = int(time.time() - w._multi_model_cache[k].get("t", 0))
+    print(f"  {k}  age={age}s")
+
+print(f"\nOM cache entries: {len(w._open_meteo_cache)}")
+print(f"Multi-model cache entries: {len(w._multi_model_cache)}")
+print(f"Rate limit until: {w._open_meteo_rate_limit_until}")