Add EnsureProperties method to EntityBaseOptions

Introduce EnsureProperties to validate required property names
against the Columns dictionary, throwing an exception if any
are missing. This helps enforce configuration completeness.

src/ReC.Infrastructure/Options/Shared/EntityBaseOptions.cs

@@ -3,4 +3,12 @@
 public record EntityBaseOptions()
 {
     public Dictionary<string, string> Columns { get; init; } = [];
+
+    public void EnsureProperties(IEnumerable<string> propertyNames)
+    {
+        var missingProperties = propertyNames.Except(Columns.Select(col => col.Key)).ToList();
+
+        if (missingProperties.Count != 0)
+            throw new InvalidOperationException($"The following properties are not configured: {string.Join(", ", missingProperties)}");
+    }
 }