feat: Add enum member extraction support across all language extractors

Extends AST parsing to identify and extract individual enum members/cases for better code analysis. Adds enumMemberTypes configuration to each language extractor with language-specific node types (e.g., 'enum_variant' for Rust, 'enum_case' for PHP, 'enum_entry' for Swift/Kotlin). Implements flexible member name resolution supporting both field-based and identifier-based extraction patterns.

src/extraction/tree-sitter-types.ts

@@ -88,6 +88,8 @@ export interface LanguageExtractor {
   structTypes: string[];
   /** Node types that represent enums */
   enumTypes: string[];
+  /** Node types that represent enum members/cases (e.g. Swift: 'enum_entry', Rust: 'enum_variant') */
+  enumMemberTypes?: string[];
   /** Node types that represent type aliases (e.g. `type X = ...`) */
   typeAliasTypes: string[];
   /** Node types that represent imports */