feat: implement Application layer for User Delete API / Application層のDeleteUserUseCase実装

[zigzagdev]

Motivation / 目的

Implement the Application layer for the User Delete API as part of #514.

ユーザー削除APIのApplication層（#516）として、DeleteUserUseCase を実装しました。

What I have done / 実施内容

• DeleteUserUseCase: handle(int $id): void
  • Command オブジェクト不要（削除に必要なのは ID のみ）
  • UserRepositroyInterface::deleteUser() を呼び出し、例外はリポジトリから自動伝播

Test Results / テスト結果

• test_handle_calls_repository_deleteUser_with_given_id
• test_handle_propagates_exception_when_user_not_found

Closes #516

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.12%. Comparing base (97ca0bf) to head (adf71bc).

Additional details and impacted files

@@                  Coverage Diff                   @@
##             feat/user-delete     #522      +/-   ##
======================================================
+ Coverage               60.01%   60.12%   +0.11%     
- Complexity               1519     1524       +5     
======================================================
  Files                     120      122       +2     
  Lines                    7778     7800      +22     
======================================================
+ Hits                     4668     4690      +22     
  Misses                   3110     3110              

Files with missing lines	Coverage Δ
...CommandUseCases/UseCase/User/DeleteUserUseCase.php	100.00% <100.00%> (ø)
...es/Tests/CommandUseCases/DeleteUserUseCaseTest.php	100.00% <100.00%> (ø)

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[zigzagdev]

Ok