Add historical data import functionality

- Add import_historical_data() method to EnhancedWaterMonitorScraper
- Support date range imports with Buddhist calendar API format
- Add CLI arguments --import-historical and --force-overwrite
- Include API rate limiting and skip existing data option
- Enable importing years of historical water level data

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/main.py

@@ -140,29 +140,68 @@ def run_gap_filling(days_back: int):
 def run_data_update(days_back: int):
     """Update existing data with latest values"""
     logger.info(f"Updating existing data for the last {days_back} days...")
-    
+
     try:
         # Validate configuration
         Config.validate_config()
-        
+
         # Initialize scraper
         db_config = Config.get_database_config()
         scraper = EnhancedWaterMonitorScraper(db_config)
-        
+
         # Update data
         updated_count = scraper.update_existing_data(days_back)
-        
+
         if updated_count > 0:
             logger.info(f"✅ Updated {updated_count} data points")
         else:
             logger.info("✅ No data updates needed")
-        
+
         return True
-        
+
     except Exception as e:
         logger.error(f"❌ Data update failed: {e}")
         return False
 
+def run_historical_import(start_date_str: str, end_date_str: str, skip_existing: bool = True):
+    """Import historical data for a date range"""
+    try:
+        # Parse dates
+        start_date = datetime.strptime(start_date_str, "%Y-%m-%d")
+        end_date = datetime.strptime(end_date_str, "%Y-%m-%d")
+
+        if start_date > end_date:
+            logger.error("Start date must be before or equal to end date")
+            return False
+
+        logger.info(f"Importing historical data from {start_date.date()} to {end_date.date()}")
+        if skip_existing:
+            logger.info("Skipping dates that already have data")
+
+        # Validate configuration
+        Config.validate_config()
+
+        # Initialize scraper
+        db_config = Config.get_database_config()
+        scraper = EnhancedWaterMonitorScraper(db_config)
+
+        # Import historical data
+        imported_count = scraper.import_historical_data(start_date, end_date, skip_existing)
+
+        if imported_count > 0:
+            logger.info(f"✅ Imported {imported_count} historical data points")
+        else:
+            logger.info("✅ No new data imported")
+
+        return True
+
+    except ValueError as e:
+        logger.error(f"❌ Invalid date format. Use YYYY-MM-DD: {e}")
+        return False
+    except Exception as e:
+        logger.error(f"❌ Historical import failed: {e}")
+        return False
+
 def run_web_api():
     """Run the FastAPI web interface"""
     logger.info("Starting web API server...")
@@ -320,6 +359,7 @@ Examples:
   %(prog)s --web-api                # Start web API server
   %(prog)s --fill-gaps 7            # Fill missing data for last 7 days
   %(prog)s --update-data 2          # Update existing data for last 2 days
+  %(prog)s --import-historical 2024-01-01 2024-01-31  # Import historical data
   %(prog)s --status                 # Show system status
   %(prog)s --alert-check            # Check water levels and send alerts
   %(prog)s --alert-test             # Send test Matrix message
@@ -352,6 +392,19 @@ Examples:
         help="Update existing data for the specified number of days back"
     )
     
+    parser.add_argument(
+        "--import-historical",
+        nargs=2,
+        metavar=("START_DATE", "END_DATE"),
+        help="Import historical data for date range (YYYY-MM-DD format)"
+    )
+
+    parser.add_argument(
+        "--force-overwrite",
+        action="store_true",
+        help="Overwrite existing data when importing historical data"
+    )
+
     parser.add_argument(
         "--status",
         action="store_true",
@@ -408,6 +461,10 @@ Examples:
             success = run_gap_filling(args.fill_gaps)
         elif args.update_data is not None:
             success = run_data_update(args.update_data)
+        elif args.import_historical is not None:
+            start_date, end_date = args.import_historical
+            skip_existing = not args.force_overwrite
+            success = run_historical_import(start_date, end_date, skip_existing)
         elif args.status:
             success = show_status()
         elif args.alert_check: