5.4.0

What's Changed

• Add vendor/bin/update-snapshots wrapper binary that sets UPDATE_SNAPSHOTS=true and runs PHPUnit. This replaces the previously documented phpunit -d --update-snapshots syntax, which abused PHPUnit's -d flag and produces a Failed to set "--update-snapshots=1" test runner warning since PHPUnit 12.5.12.
• Drop the phpunit -d --without-creating-snapshots form from the README. Use the CREATE_SNAPSHOTS=false environment variable instead. The argv check is kept in shouldCreateSnapshots() for backwards compatibility.
• The wrapper restores the prior UPDATE_SNAPSHOTS env var state on shutdown, so it does not leak a state mutation to any in-process code that runs after PHPUnit.
• Reworded the "Snapshot does not exist" failure message and the "snapshots can be updated by..." prompt to point at the new approach.
• shouldUpdateSnapshots() and shouldCreateSnapshots() now check the env var first, then fall back to the legacy CLI argument.
• Fix tests on PHPUnit 12.5+, where mocks throwing AssertionFailedError are tracked as a test failure even when user code catches the exception. The expectFail helper now uses a plain RuntimeException carrying the expected message.

Closes #242.

Full Changelog: 5.3.2...5.4.0