feat: implement Presentation layer for User Login and introduce mago lint / ユーザーログインのPresentation層実装とmago lint導入

[zigzagdev]

Motivation / 目的

Implement the Presentation layer for the User Login API (#405) and introduce mago as a static analysis tool for CI.

ユーザーログインAPI（#405）のPresentation層を実装し、静的解析ツールとしてmago lintをCIに導入しました。

What I have done / 実施内容

Presentation layer

• AuthController: POST /api/v1/user/login のアクションを実装
  • 正常時: 200 + { token, token_type: "Bearer" }
  • 認証失敗時: 401
  • その他エラー: 500
• routes/api.php: /v1/user/login ルートを登録、Route::controller() でルートをグループ化

Static Analysis

• mago.toml: lintベースの静的解析設定を追加
  • スコープ: app, config, database, routes
  • セキュリティ・バグ系ルールを有効化、スタイル系は無効化
• .github/workflows/static_analysis.yml: PR時に mago lint を実行するCIワークフローを追加

Other

• .gitignore: .composer を追加（Dockerコンテナが生成するキャッシュを除外）

Test Results / テスト結果

Integration tests hitting the real DB:

• test_login_returns_200_with_token_on_valid_credentials
• test_login_returns_401_when_user_not_found
• test_login_returns_401_on_wrong_password

Closes #528

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.64%. Comparing base (f382085) to head (16fc4df).
⚠️ Report is 10 commits behind head on feat/user-login.

Additional details and impacted files

@@                  Coverage Diff                  @@
##             feat/user-login     #534      +/-   ##
=====================================================
+ Coverage              61.22%   61.64%   +0.42%     
- Complexity              1569     1581      +12     
=====================================================
  Files                    129      131       +2     
  Lines                   8048     8138      +90     
=====================================================
+ Hits                    4927     5017      +90     
  Misses                  3121     3121              

Files with missing lines	Coverage Δ
...ures/CommandUseCases/UseCase/User/LoginUseCase.php	100.00% <ø> (ø)
...pp/Packages/Features/Controller/AuthController.php	100.00% <100.00%> (ø)
src/app/Packages/Features/Tests/LoginTest.php	100.00% <100.00%> (ø)

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[zigzagdev]

LGTM