[FEAT/#112] 토큰 인증 실패 시 응답 상태 코드 오류 수정 및 인증 필터·화이트리스트 정비

[ckkim817]

💡 Issue

• resolved: [FIX] 토큰 인증 실패 시 응답 상태 코드 오류 수정 및 인증 필터·화이트리스트 정비 #112

📄 Description

• 액세스 토큰 만료 등으로 인한 토큰 인증 실패 시 401이 아닌 403 에러를 반환하던 오류를 수정했습니다.
• 인증 필터의 Bearer 파싱을 보강하고, 토큰 검증 및 예외 처리 로직을 401 에러 응답으로 통일했습니다.
• v2 버저닝 추가에 따라 SecurityConfig의 화이트리스트를 정비했습니다.

[Copilot]

Pull Request Overview

This PR addresses token authentication failures by fixing status code errors and refactoring authentication filters. The primary issue was returning 403 (Forbidden) instead of 401 (Unauthorized) for expired or invalid tokens.

• Fixed HTTP status code from 403 to 401 for JWT authentication failures
• Enhanced Bearer token parsing and validation in authentication filter
• Updated whitelist configuration for v2 API versioning

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
SecurityConfig.java	Updated whitelist to include v2 auth endpoints and cleaned up configuration formatting
JwtAuthenticationException.java	Added new custom exception class for JWT authentication errors
JwtAuthenticationFilter.java	Refactored token validation logic with proper exception handling and Bearer token parsing
CustomJwtAuthenticationEntryPoint.java	Fixed status code from 403 to 401 for authentication failures

[Copilot]

The error message should be more descriptive. Consider adding context about the internal error: "Internal error: VALID_JWT token should not be mapped to an authentication exception"

Suggested change

	case VALID_JWT -> throw new IllegalStateException("VALID_JWT should not reach mapToAuthException");
	case VALID_JWT -> throw new IllegalStateException("Internal error: VALID_JWT token should not be mapped to an authentication exception. This indicates a logic error in the authentication flow. Please check the JWT validation and filter logic.");