fix(api): lowercase default metric names to match ALLOWED_METRICS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/beanflows/api/routes.py

@@ -136,7 +136,7 @@ async def list_commodities():
 @api_key_required(scopes=["read"])
 async def commodity_metrics(code: int):
     """Time series metrics for a commodity. Query params: metrics, start_year, end_year."""
-    raw_metrics = request.args.getlist("metrics") or ["Production", "Exports", "Imports", "Ending_Stocks"]
+    raw_metrics = request.args.getlist("metrics") or ["production", "exports", "imports", "ending_stocks"]
     metrics = [m for m in raw_metrics if m in analytics.ALLOWED_METRICS]
     if not metrics:
         return jsonify({"error": f"No valid metrics. Allowed: {sorted(analytics.ALLOWED_METRICS)}"}), 400
@@ -152,7 +152,7 @@ async def commodity_metrics(code: int):
 @api_key_required(scopes=["read"])
 async def commodity_countries(code: int):
     """Country ranking for a commodity. Query params: metric, limit."""
-    metric = request.args.get("metric", "Production")
+    metric = request.args.get("metric", "production")
     if metric not in analytics.ALLOWED_METRICS:
         return jsonify({"error": f"Invalid metric. Allowed: {sorted(analytics.ALLOWED_METRICS)}"}), 400
 
@@ -368,7 +368,7 @@ async def commodity_metrics_csv(code: int):
         return jsonify({"error": "CSV export requires a Starter or Pro plan"}), 403
 
     raw_metrics = request.args.getlist("metrics") or [
-        "Production", "Exports", "Imports", "Ending_Stocks", "Total_Distribution",
+        "production", "exports", "imports", "ending_stocks", "total_distribution",
     ]
     metrics = [m for m in raw_metrics if m in analytics.ALLOWED_METRICS]
     if not metrics: