Fix critical error handling gaps in submission pipeline

Addressed real error handling issues identified during comprehensive
pipeline review:

1. **process-selective-approval edge function**
   - Added try-catch blocks around idempotency key updates (lines 216-262)
   - Prevents silent failures when updating submission status tracking
   - Updates are now non-blocking to ensure proper response delivery

2. **submissionItemsService.ts**
   - Added error logging before throwing in fetchSubmissionItems (line 75-81)
   - Added error handling for park location fetch failures (lines 99-107)
   - Location fetch errors are now logged as non-critical and don't block
     submission item retrieval

3. **notify-moderators-submission edge function**
   - Added error handling for notification log insert (lines 216-236)
   - Log failures are now non-blocking and properly logged
   - Ensures notification delivery isn't blocked by logging issues

4. **upload-image edge function**
   - Fixed CORS headers scope issue (line 127)
   - Moved corsHeaders definition outside try block
   - Prevents undefined reference in catch block error responses

All changes maintain backward compatibility and improve pipeline
resilience without altering functionality. Error handling is now
consistent with non-blocking patterns for auxiliary operations.

src/lib/submissionItemsService.ts

@@ -72,7 +72,13 @@ export async function fetchSubmissionItems(submissionId: string): Promise<Submis
     .eq('submission_id', submissionId)
     .order('order_index', { ascending: true });
 
-  if (error) throw error;
+  if (error) {
+    handleError(error, {
+      action: 'Fetch Submission Items',
+      metadata: { submissionId }
+    });
+    throw error;
+  }
   
   // Transform data to include relational data as item_data
   return await Promise.all((data || []).map(async item => {
@@ -84,14 +90,23 @@ export async function fetchSubmissionItems(submissionId: string): Promise<Submis
         // Fetch location from park_submission_locations if available
         let locationData: any = null;
         if (parkSub?.id) {
-          const { data } = await supabase
+          const { data, error: locationError } = await supabase
             .from('park_submission_locations')
             .select('*')
             .eq('park_submission_id', parkSub.id)
             .maybeSingle();
-          locationData = data;
+
+          if (locationError) {
+            handleNonCriticalError(locationError, {
+              action: 'Fetch Park Submission Location',
+              metadata: { parkSubmissionId: parkSub.id, submissionId }
+            });
+            // Continue without location data - non-critical
+          } else {
+            locationData = data;
+          }
         }
-        
+
         item_data = {
           ...parkSub,
           // Transform park_submission_location → location for form compatibility