Make GetValueByColumnName a generic extension method

Refactored GetValueByColumnName to use a generic type parameter constrained to class types. This enhances type safety and enables better type inference and static analysis when accessing property values by column name.

src/ReC.Domain/Extensions/ReflectionExtensions.cs

@@ -9,7 +9,7 @@ public static class ReflectionExtensions
     /// Gets the value of a property by its column name defined in <see cref="ColumnAttribute"/>.
     /// Returns <c>null</c> if no property with the given column name exists.
     /// </summary>
-    public static object? GetValueByColumnName(this object obj, string columnName)
+    public static object? GetValueByColumnName<T>(this T obj, string columnName) where T : class
     {
         var property = obj.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance)
             .FirstOrDefault(p => p.GetCustomAttribute<ColumnAttribute>()?.Name == columnName);