Change ExecuteDynamicSqlAsync to return object list

The ExecuteDynamicSqlAsync method now returns an IEnumerable of
dictionaries representing query result rows, instead of a JSON
string. This allows consumers to work directly with the data
in its native .NET object form.

src/ReC.Application/Common/Interfaces/IRecDbContext.cs

@@ -30,7 +30,7 @@ public interface IRecDbContext
 public static class RecDbContextSaveExtensions
 {
     //TODO: Once it is finalized, move it to Common.Infrastructure
-    public static async Task<string> ExecuteDynamicSqlAsync(this IRecDbContext context, string sql, CancellationToken cancel = default)
+    public static async Task<IEnumerable<Dictionary<string, object?>>> ExecuteDynamicSqlAsync(this IRecDbContext context, string sql, CancellationToken cancel = default)
     {
         var result = new List<Dictionary<string, object?>>();
 
@@ -56,6 +56,6 @@ public static class RecDbContextSaveExtensions
             result.Add(row);
         }
 
-        return JsonSerializer.Serialize(result);
+        return result;
     }
 }