This PR implements a decorator-based API that enables parameter validation for class methods using typia's type-checking capabilities.

Problem

Currently, typia only supports functional wrappers for method validation:

classUserService{findMany(query:UserQuery):UserQuery[]{return[query];}}// Must wrap methods manuallyconstservice=newUserService();constwrappedFindMany=typia.functional.assertEqualsParameters(service.findMany.bind(service));

This approach is verbose and doesn't integrate cleanly with class-based architectures.

Solution

This PR introduces decorator support that enables clean, declarative validation:

classUserService{    @typia.decorators.assertEquals()findMany(query:UserQuery):UserQuery[]{return[query];// Parameters are automatically validated}}

Implementation

• Newsrc/decorators.ts module with decorator functions (assert,assertEquals,is,equals,validate,validateEquals)
• Transformer integration viaCallExpressionTransformer to handletypia.decorators.* calls
• Decorator transformer pipeline that generates validation decorator functions
• Reuse of existing validation logic from the functional module

The decorators are transformed at compile-time to return proper TypeScript decorators that wrap methods with validation logic, maintaining typia's zero-runtime-overhead philosophy.

Fixes#1586

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