feat: LocalDateRangeとLocalDateTimeRangeクラスを実装

[endou-mame]

Summary

• 日付と日時の範囲を表すValueObjectクラスを実装
• php-monadを本番依存に移動（Result/Option型の利用のため）

追加した機能

LocalDateRange

• 日付の範囲を表す値オブジェクト
• 開始日と終了日、範囲タイプを保持
• 範囲内包含判定、重なり判定、期間計算機能

LocalDateTimeRange

• 日時の範囲を表す値オブジェクト
• 開始日時と終了日時、範囲タイプを保持
• 範囲内包含判定、重なり判定、期間計算機能

RangeType

• 範囲の境界タイプを表す列挙型
• CLOSED（閉区間）、OPEN（開区間）、HALF_OPEN_LEFT（左開区間）、HALF_OPEN_RIGHT（右開区間）

Test plan

• LocalDateRangeの単体テストを実装
• LocalDateTimeRangeの単体テストを実装
• 境界値テストを含む包括的なテストケース
• 使用例をexamplesディレクトリに追加

Fixes #29

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

Implements value objects for date and datetime ranges (LocalDateRange, LocalDateTimeRange) with a shared RangeType enum, comprehensive tests/examples, and promotes wiz-develop/php-monad to a runtime dependency.

• Added RangeType enum to express open/closed/hybrid intervals
• Introduced LocalDateRange and LocalDateTimeRange classes with validation, serialization, containment, overlap, and iteration
• Updated composer.json to require wiz-develop/php-monad and removed it from dev dependencies

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
composer.json	Moved wiz-develop/php-monad from dev to runtime require
src/DateTime/RangeType.php	Added RangeType enum for interval boundary types
src/DateTime/LocalDateTimeRange.php	Implemented datetime range value object
src/DateTime/LocalDateRange.php	Implemented date range value object
tests/Unit/Enum/EnumValueTest.php	Added phpstan ignore annotation in a test
tests/Unit/DateTime/LocalDateTimeRangeTest.php	Added unit tests covering all datetime‐range behaviors
tests/Unit/DateTime/LocalDateRangeTest.php	Added unit tests covering all date‐range behaviors

Comments suppressed due to low confidence (3)

src/DateTime/LocalDateTimeRange.php:7

• The use Override; import is unresolved. Either remove this if unused or import the correct attribute namespace (e.g., use JetBrains\PhpStorm\Override;).

use Override;

src/DateTime/LocalDateRange.php:8

• The use Override; import is unresolved. Either remove this if unused or import the correct attribute namespace (e.g., use JetBrains\PhpStorm\Override;).

use Override;

tests/Unit/DateTime/LocalDateRangeTest.php:340

• [nitpick] The test name indicates "default is open" but asserts a CLOSED range. Rename the test to reflect that the default is a CLOSED interval.

public function test_from_デフォルトは開区間(): void