feat: 泛型基础设施 — <T>解析 + 类型推断 (单态化 codegen 待补)

src/ast/ast.h

@@ -67,7 +67,8 @@ struct AstNode {
         // AST_FUNCTION
         struct { const char* name; struct AstNode** params; size_t param_count;
                  TypeKind return_type; const char* return_struct_type_name;
-                 struct AstNode* body; bool is_pub; } function;
+                 struct AstNode* body; bool is_pub;
+                 const char** type_params; size_t type_param_count; } function;
         // AST_PARAMETER (也用作结构体字段: name + type)
         struct { const char* name; TypeKind type; const char* struct_type_name; } parameter;
         // AST_BLOCK
@@ -137,7 +138,8 @@ AstNode* ast_make_program(void* alloc, AstNode** fns, size_t fn_count,
                           AstNode** impls, size_t impl_count, SourceLoc loc);
 AstNode* ast_make_function(void* alloc, const char* name, AstNode** params, size_t pcount,
                            TypeKind ret, const char* ret_struct_name, AstNode* body,
-                           bool is_pub, SourceLoc loc);
+                           bool is_pub, const char** type_params, size_t tp_count,
+                           SourceLoc loc);
 AstNode* ast_make_parameter(void* alloc, const char* name, TypeKind type, const char* struct_type_name, SourceLoc loc);
 AstNode* ast_make_block(void* alloc, AstNode** stmts, size_t count, SourceLoc loc);
 AstNode* ast_make_let(void* alloc, const char* name, TypeKind annot_type, bool has_type_annot,