接入新加坡 MSS 1分钟实时温度及 MGM/JMA/FMI/KNMI 高频源到 airport_primary

- 新建 singapore_mss_sources.py：拉取 data.gov.sg 1分钟干球温度（S24 樟宜站）
- country_networks.py：_airport_primary_from_raw 新增 MGM/JMA/FMI/KNMI/SG_MSS 分支
- weather_sources.py：注入 jma_current/fmi_current/knmi_current/singapore_mss_current
- 前端 MonitorPanel：resolveSourceLabel 根据 airport_primary.source_code 显示数据源标签
- 文档：更新 AIRPORT_REALTIME_SOURCES.md 新增新加坡

Tested: ruff check . ✓  npx tsc --noEmit ✓

src/data_collection/singapore_mss_sources.py

@@ -0,0 +1,132 @@
+"""Singapore MSS 1-minute real-time temperature data source.
+
+Fetches air temperature from data.gov.sg public API.
+The API provides dry-bulb temperature (1-min mean) at ~1 min interval
+from 15 stations across Singapore. Station S24 (Upper Changi Road North)
+is the closest to Changi Airport (WSSS).
+
+URL: https://api.data.gov.sg/v1/environment/air-temperature
+"""
+
+from __future__ import annotations
+
+import time
+from datetime import datetime, timezone
+from typing import Any, Dict, Optional
+
+from loguru import logger
+
+from src.utils.metrics import record_source_call
+
+SINGAPORE_MSS_TEMP_URL = (
+    "https://api.data.gov.sg/v1/environment/air-temperature"
+)
+
+# Preferred station: closest to Changi Airport (WSSS)
+PREFERRED_STATION_ID = "S24"
+PREFERRED_STATION_NAME = "Upper Changi Road North"
+
+
+def _parse_mss_reading(raw: Dict[str, Any]) -> Optional[Dict[str, Any]]:
+    """Extract the preferred station's temperature from an API response."""
+    items = raw.get("items") or []
+    if not items:
+        return None
+
+    metadata = raw.get("metadata") or {}
+    stations = metadata.get("stations") or []
+
+    # Resolve station name
+    station_name = ""
+    for s in stations:
+        if isinstance(s, dict) and s.get("id") == PREFERRED_STATION_ID:
+            station_name = str(s.get("name") or PREFERRED_STATION_NAME)
+            break
+    if not station_name:
+        station_name = PREFERRED_STATION_NAME
+
+    # Take the most recent reading
+    latest = items[-1]
+    readings = latest.get("readings") or []
+    ts = str(latest.get("timestamp") or "")
+
+    for r in readings:
+        if r.get("station_id") == PREFERRED_STATION_ID:
+            temp_c = r.get("value")
+            if temp_c is not None and -20 < temp_c < 55:
+                # Observed at: use the API timestamp, which is UTC+8
+                obs_time = ts
+                if obs_time:
+                    try:
+                        dt = datetime.fromisoformat(obs_time)
+                        obs_time = dt.astimezone(timezone.utc).isoformat()
+                    except (ValueError, OverflowError):
+                        pass
+
+                return {
+                    "station_id": PREFERRED_STATION_ID,
+                    "station_name": station_name,
+                    "temp_c": round(float(temp_c), 1),
+                    "obs_time": obs_time,
+                    "source": "sg_mss",
+                }
+
+    return None
+
+
+class SingaporeMssSourceMixin:
+    """Mixin that adds Singapore MSS 1-min data to WeatherDataCollector."""
+
+    def _sg_mss_http_get(self, url: str) -> Optional[Dict[str, Any]]:
+        getter = getattr(self, "_http_get", None)
+        if callable(getter):
+            resp = getter(url)
+            if hasattr(resp, "json"):
+                return resp.json()
+            return resp
+        try:
+            resp = self.session.get(url, timeout=self.timeout)
+            resp.raise_for_status()
+            return resp.json()
+        except Exception:
+            return None
+
+    def fetch_singapore_mss_current(self) -> Optional[Dict[str, Any]]:
+        """Fetch latest Singapore MSS temperature for Changi station."""
+        started = time.perf_counter()
+
+        try:
+            raw = self._sg_mss_http_get(SINGAPORE_MSS_TEMP_URL)
+            if not raw:
+                record_source_call(
+                    "sg_mss", "current", "empty",
+                    (time.perf_counter() - started) * 1000.0,
+                )
+                return None
+
+            result = _parse_mss_reading(raw)
+            if result:
+                logger.info(
+                    "Singapore MSS: station={} temp={}°C obs_time={}",
+                    result["station_id"],
+                    result["temp_c"],
+                    result.get("obs_time", "?"),
+                )
+                record_source_call(
+                    "sg_mss", "current", "success",
+                    (time.perf_counter() - started) * 1000.0,
+                )
+            else:
+                record_source_call(
+                    "sg_mss", "current", "no_station",
+                    (time.perf_counter() - started) * 1000.0,
+                )
+            return result
+
+        except Exception as exc:
+            logger.warning("Singapore MSS fetch failed: {}", exc)
+            record_source_call(
+                "sg_mss", "current", "error",
+                (time.perf_counter() - started) * 1000.0,
+            )
+            return None