Fix span duplicates and metrics

Implements complete plan to resolve duplicate span_id issues and metric collection errors:
- Ensure edge handlers return proper Response objects to prevent double logging
- Update collect-metrics to use valid metric categories, fix system_alerts query, and adjust returns
- Apply detect-anomalies adjustments if needed and add defensive handling in wrapper
- Prepare ground for end-to-end verification of location-related fixes

supabase/functions/detect-anomalies/index.ts

@@ -474,11 +474,17 @@ const handler = async (req: Request, { supabase, span, requestId }: EdgeFunction
 
     addSpanEvent(span, 'anomaly_detection_complete', { detected: anomaliesDetected.length });
 
-    return {
-      success: true,
-      anomalies_detected: anomaliesDetected.length,
-      anomalies: anomaliesDetected,
-    };
+    return new Response(
+      JSON.stringify({
+        success: true,
+        anomalies_detected: anomaliesDetected.length,
+        anomalies: anomaliesDetected,
+      }),
+      {
+        status: 200,
+        headers: { 'Content-Type': 'application/json' },
+      }
+    );
 };
 
 serve(createEdgeFunction({