fix(dashboard): Fix grammar in grouped activity messages

Changed "10 scan completeds" to "10 scans completed" by fixing the
pluralization logic. The previous code appended 's' to the entire
phrase instead of just the noun.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: remyluslosius

frontend/src/components/dashboard/ActivityFeed.tsx

@@ -202,7 +202,7 @@ const ActivityFeed: React.FC<ActivityFeedProps> = ({
                       <Box sx={{ display: 'flex', alignItems: 'center', gap: 1 }}>
                         <Typography variant="body2" sx={{ wordBreak: 'break-word' }}>
                           {isGrouped
-                            ? `${group.items.length} ${firstItem.type.replace('_', ' ')}s`
+                            ? `${group.items.length} ${firstItem.type.replace('_', 's ')}`
                             : firstItem.message}
                         </Typography>
                         {firstItem.metadata?.complianceScore !== undefined &&