feat: Add C# property/field extraction and inheritance support

Addresses C#'s property_declaration nodes (public string Name { get; set; }) by adding propertyTypes support and extractProperty method. Improves field extraction to handle C#'s nested variable_declaration > variable_declarator structure. Adds base_list handling in extractInheritance for C#'s `: Parent, IInterface` syntax where base class and interfaces are combined in a single colon-separated list.

src/extraction/languages/csharp.ts

@@ -15,6 +15,7 @@ export const csharpExtractor: LanguageExtractor = {
   callTypes: ['invocation_expression'],
   variableTypes: ['local_declaration_statement'],
   fieldTypes: ['field_declaration'],
+  propertyTypes: ['property_declaration'],
   nameField: 'name',
   bodyField: 'body',
   paramsField: 'parameter_list',