Tel Aviv 机场观测切换至 IMS Lod Airport 实时数据源

新增 IMS (Israel Meteorological Service) 数据抓取模块，以 Lod Airport
(station 225) 官方观测替代 NOAA METAR LLBG 作为 airport_primary。
IMS 数据接入 _airport_primary_from_raw 优先级链，高于 plain METAR
但保留 METAR 集群回退路径。

Constraint: IMS API (ims.gov.il/en/hourly_observations) 仅每小时更新
Confidence: high
Scope-risk: 仅影响 Tel Aviv 城市，其余 51 城数据流不变
Tested: 端到端验证 IMS 取数 → airport_primary → provider 路由链

src/data_collection/ims_sources.py

@@ -0,0 +1,100 @@
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Dict, Optional
+
+from loguru import logger
+
+from src.utils.metrics import record_source_call
+
+
+class ImsSourceMixin:
+    """Fetch realtime observations from Israel Meteorological Service (IMS).
+
+    The IMS public API at /en/hourly_observations returns a JSON payload with
+    data.hourly_observations_map keyed by timestamp and station ID, covering all
+    active IMS stations for the current day.
+
+    Station 225 = Lod Airport (Ben Gurion / LLBG), elevation 40 m.
+    """
+
+    IMS_LOD_AIRPORT_STATION = "225"
+    IMS_OBSERVATIONS_URL = "https://ims.gov.il/en/hourly_observations"
+
+    def fetch_from_ims(self, station_id: str = "225") -> Optional[Dict]:
+        started = datetime.now()
+
+        def _elapsed_ms() -> float:
+            return (datetime.now() - started).total_seconds() * 1000.0
+
+        try:
+            resp = self._http_get(self.IMS_OBSERVATIONS_URL, timeout=self.timeout)
+            if resp.status_code != 200:
+                logger.warning("IMS API returned HTTP {}", resp.status_code)
+                record_source_call("ims", "station", "error", _elapsed_ms())
+                return None
+
+            body = resp.json()
+            obs_map = (body.get("data") or {}).get("hourly_observations_map") or {}
+            if not obs_map:
+                record_source_call("ims", "station", "empty", _elapsed_ms())
+                return None
+
+            latest_time = max(obs_map.keys())
+            latest = obs_map[latest_time].get(station_id) or {}
+            if not latest:
+                record_source_call("ims", "station", "empty", _elapsed_ms())
+                return None
+
+            def _f(key: str) -> Optional[float]:
+                raw = latest.get(key)
+                if raw is None:
+                    return None
+                try:
+                    return float(raw)
+                except (ValueError, TypeError):
+                    return None
+
+            temp = _f("TT")
+            rh = _f("RH")
+            wind_kmh = _f("FF")
+            wind_dir = _f("DD")
+            tx1 = _f("TX1")
+            tn1 = _f("TN1")
+            td = _f("TD")
+
+            wind_kt = round(wind_kmh / 1.852, 1) if wind_kmh is not None else None
+
+            result: Dict = {
+                "current": {
+                    "temp": temp,
+                    "humidity": rh,
+                    "wind_speed_kmh": wind_kmh,
+                    "wind_speed_kt": wind_kt,
+                    "wind_dir": wind_dir,
+                    "dew_point": td,
+                    "max_temp_so_far": tx1,
+                    "min_temp_so_far": tn1,
+                },
+                "obs_time": latest_time,
+                "station_id": station_id,
+                "station_label": "Lod Airport",
+                "lat": 32.002943,
+                "lon": 34.891534,
+                "elevation_m": 40,
+            }
+            record_source_call("ims", "station", "success", _elapsed_ms())
+            logger.info(
+                "IMS Lod Airport (s{}) {}: temp={}°C RH={}% wind={}km/h",
+                station_id,
+                latest_time,
+                temp,
+                rh,
+                wind_kmh,
+            )
+            return result
+
+        except Exception:
+            logger.exception("IMS fetch failed for station {}", station_id)
+            record_source_call("ims", "station", "error", _elapsed_ms())
+            return None