接入 FMI 赫尔辛基-万塔机场 10 分钟实时数据源

新增 fmi_sources.py，通过 FMI Open Data WFS API 获取 Helsinki-Vantaa
机场观测数据（FMISID 100968, WMO 2974）。每 10 分钟更新，参数含温度/
风速/气压。免费无需 API key。集成至高频机场推送体系。

Constraint: FMI WFS 无 rate limit，无需注册
Scope-risk: 中，新增数据源
Tested: pytest 176 passed, FMI 实测 temp=13.1°C wind=9.5kt pressure=1000.9hPa

src/utils/telegram_push.py

@@ -690,8 +690,8 @@ def start_trade_alert_push_loop(bot: Any, config: Dict[str, Any]) -> Optional[th
 
 # ── high-freq airport push loop ──
 
-HIGH_FREQ_AIRPORT_CITIES = {"seoul", "busan", "tokyo", "ankara"}
-HIGH_FREQ_AIRPORT_ICAO = {"seoul": "RKSI", "busan": "RKPK", "tokyo": "RJTT", "ankara": "17128"}
+HIGH_FREQ_AIRPORT_CITIES = {"seoul", "busan", "tokyo", "ankara", "helsinki"}
+HIGH_FREQ_AIRPORT_ICAO = {"seoul": "RKSI", "busan": "RKPK", "tokyo": "RJTT", "ankara": "17128", "helsinki": "EFHK"}
 
 _AIRPORT_PUSH_STATE_PATH = os.path.join(
     os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))),
@@ -723,7 +723,7 @@ def _save_airport_state(state: Dict[str, Any]) -> None:
     os.replace(tmp, path)
 
 
-_AIRPORT_CITY_LABEL = {"seoul": "首尔/仁川", "busan": "釜山/金海", "tokyo": "东京/羽田", "ankara": "安卡拉/Esenboğa"}
+_AIRPORT_CITY_LABEL = {"seoul": "首尔/仁川", "busan": "釜山/金海", "tokyo": "东京/羽田", "ankara": "安卡拉/Esenboğa", "helsinki": "赫尔辛基/Vantaa"}
 
 
 def _build_airport_status_message(