feat: hourly HII/ThaiWater rainfall + backup water-level collection

Poll the open api-v3.thaiwater.net public endpoints (rain_24h,
waterlevel_load), filter to the Ping basin, and persist to new
hii_rain_stations/hii_rainfall and hii_wl_stations/hii_waterlevel tables
(auto-created; sqlite/postgresql/mysql). Water levels stay in their own
tables since HII reports m MSL from a different station set; rid_code
maps mirrors like ridhydro_P.1 to P.1 and offset_msl converts MSL to
gauge datum. Runs every scraping cycle in web-api and continuous modes
(hourly cadence even during 1-minute RID retry), one-shot via
--collect-hii; docs/DATA_SOURCES.md catalogs all probed endpoints.

src/config.py

@@ -78,6 +78,15 @@ class Config:
     # MySQL settings
     MYSQL_CONNECTION_STRING = os.getenv("MYSQL_CONNECTION_STRING")
 
+    # HII/ThaiWater open api-v3 collection (rainfall + backup water level)
+    # See docs/DATA_SOURCES.md. Requires a SQL DB_TYPE (sqlite/postgresql/mysql).
+    ENABLE_HII_COLLECTION = os.getenv("ENABLE_HII_COLLECTION", "true").lower() in (
+        "1",
+        "true",
+        "yes",
+    )
+    HII_BASIN_CODE = int(os.getenv("HII_BASIN_CODE", "6"))  # 6 = Ping Basin
+
     # Scheduler settings
     SCRAPING_INTERVAL_HOURS = int(os.getenv("SCRAPING_INTERVAL_HOURS", "1"))