Unlink child suggestions and clear votes on delete

Endpoints/SuggestEndpoints.cs

@@ -111,6 +111,14 @@ public static class SuggestEndpoints
             if (suggestion == null)
                 return Results.NotFound(new { error = "Suggestion not found." });
 
+            // Break any links that pointed at this suggestion
+            await db.Suggestions
+                .Where(s => s.ParentSuggestionId == suggestion.Id)
+                .ExecuteUpdateAsync(s => s.SetProperty(x => x.ParentSuggestionId, (int?)null));
+
+            // Remove votes for this suggestion to avoid orphaned vote rows or FK errors
+            await db.Votes.Where(v => v.SuggestionId == suggestion.Id).ExecuteDeleteAsync();
+
             db.Suggestions.Remove(suggestion);
             await db.SaveChangesAsync();
             return Results.NoContent();