프로필 수정 + Header 아바타 + MateBoard 본인글 표시 — POP-SPOT v2.16

// v2.16 — UserProfileController.java (신규)
@RestController
@RequestMapping("/api/v1/users/me/profile")
public class UserProfileController {

  private final UserProfileService service;

  public UserProfileController(UserProfileService service) {
    this.service = service;
  }

  @PatchMapping
  public UserProfileResponse updateProfile(
      Authentication auth,
      @RequestBody @Valid ProfileUpdateRequest req) {
    Long userId = Long.parseLong(auth.getName());
    return service.updateProfile(userId, req);
  }

  @PostMapping(value = "/image",
               consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
  public UserProfileResponse updateImage(
      Authentication auth,
      @RequestPart("file") MultipartFile file) {
    Long userId = Long.parseLong(auth.getName());
    return service.updateProfileImage(userId, file);
  }
}

// v2.16 — UserProfileService.updateProfile()
@Transactional
public UserProfileResponse updateProfile(Long userId, ProfileUpdateRequest req) {
  User user = userRepository.findById(userId)
      .orElseThrow(() -> new ResourceNotFoundException("User"));

  if (req.name() != null) {
    String safe = req.name().trim();
    if (safe.length() < 2 || safe.length() > 20) {
      throw new BadRequestException("이름은 2~20자");
    }
    user.changeName(safe);
  }
  return UserProfileResponse.from(user);
}

// v2.16 — profile/edit/page.tsx (신규)
'use client';
export default function ProfileEditPage() {
  const [name, setName] = useState('');
  const [file, setFile] = useState<File | null>(null);

  async function handleSave() {
    await fetch('/api/v1/users/me/profile', {
      method: 'PATCH',
      headers: { 'Content-Type': 'application/json' },
      credentials: 'include',
      body: JSON.stringify({ name }),
    });

    if (file) {
      const fd = new FormData();
      fd.append('file', file);
      await fetch('/api/v1/users/me/profile/image', {
        method: 'POST',
        credentials: 'include',
        body: fd,
      });
    }

    router.push('/?tab=MY');
  }
}

// v2.16 — Header.tsx 우상단 아바타 블록
{user && (
  <div className="flex items-center gap-2">
    <Avatar src={user.profileImageUrl} name={user.name} size={28} />
    <span className="hidden md:inline-flex text-sm font-medium">
      {user.name}
    </span>
    {user.isPremium && (
      <span className="hidden md:inline-flex text-[10px] px-1.5 py-0.5
                       rounded bg-amber-400/20 text-amber-700">
        PRO
      </span>
    )}
  </div>
)}

// v2.16 — MateBoard.tsx 내 각 카드 렌더링 쪽
{post.authorId === currentUserId && (
  <span className="inline-flex items-center gap-1 text-[10px]
                   px-2 py-0.5 rounded-full
                   bg-lime-400/15 text-lime-700 font-medium">
    내 글
  </span>
)}