Add assert is list

[frankdekker]

Adds Assert::isList to assert an array is of type list<mixed>

Added phpstan extension to preserve value type information, as this was not possible with phpstan standard docblock notation.

Scenarios:

• in: mixed, out: list<mixed>
• in: int[], out: list<int>
• in: array<int|string..>, out: list<int|string..>

Security advisories

Had to remove PHPUnit 10 + 11 due to:

Root composer.json requires phpunit/phpunit ^10.2 || ^11.0, found phpunit/phpunit[10.2.0, ..., 10.5.63, 11.0.0, ..., 11.5.55] but these were not loaded, because they are affected by security advisories. To ignore the advisories, add ("PKSA-5jz8-6tcw-pbk4") to the audit "ignore" config.

[Copilot]

Pull request overview

Adds a new Assert::isList() assertion to complement existing Assert::isArray() behavior, and introduces a PHPStan dynamic return type extension so isList() preserves element type information as list<V> during static analysis.

Changes:

• Added Assert::isList(mixed $value): array runtime assertion using array_is_list().
• Added a PHPStan DynamicStaticMethodReturnTypeExtension + integration tests to infer list<V> while preserving value types.
• Updated configuration (extension.neon) and documentation (README.md) to expose/register the new feature.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Assert.php	Adds Assert::isList() runtime assertion method.
src/PHPStan/Extension/AssertIsListReturnExtension.php	Adds PHPStan dynamic return type extension for Assert::isList().
extension.neon	Registers the new PHPStan extension service.
tests/Unit/AssertTest.php	Adds unit tests for isList() success and failure modes.
tests/Integration/PHPStan/AssertIsListExtensionTest.php	Adds PHPStan type-inference test harness for the new extension.
tests/Integration/PHPStan/data/AssertIsListAssertions.php	Provides assertType() cases validating inferred list/value types.
README.md	Documents isList in the Assert method list.

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