chore: add public API snapshot check

[marandaneto]

💡 Motivation and Context

Adds a public API snapshot check so accidental public API changes are caught in CI before release. The snapshot generator normalizes self/parent type names so the generated JSON stays stable across supported PHP versions.

💚 How did you test it?

• composer api:check
• composer validate --no-check-lock --no-check-version --strict
• php -l scripts/PublicApiSnapshot.php
• php phpcs.phar --standard=phpcs.xml --no-colors scripts/PublicApiSnapshot.php scripts/check-public-api.php

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
scripts/PublicApiSnapshot.php:170
`getInterfaceNames()` returns interfaces in an implementation-defined order. Sorting the list before storing it guarantees a stable snapshot regardless of PHP version or internal ordering changes, avoiding false-positive diffs.

```suggestion
            'implements' => array_values(array_unique($class->getInterfaceNames())),
```

_{Reviews (1): Last reviewed commit: "fix: stabilize public API type snapshots" | Re-trigger Greptile}

[greptile-apps]

getInterfaceNames() returns interfaces in an implementation-defined order. Sorting the list before storing it guarantees a stable snapshot regardless of PHP version or internal ordering changes, avoiding false-positive diffs.

Suggested change

	'implements' => array_values($class->getInterfaceNames()),
	'implements' => array_values(array_unique($class->getInterfaceNames())),

Prompt To Fix With AI

This is a comment left during a code review.
Path: scripts/PublicApiSnapshot.php
Line: 170

Comment:
`getInterfaceNames()` returns interfaces in an implementation-defined order. Sorting the list before storing it guarantees a stable snapshot regardless of PHP version or internal ordering changes, avoiding false-positive diffs.

```suggestion
            'implements' => array_values(array_unique($class->getInterfaceNames())),
```

How can I resolve this? If you propose a fix, please make it concise.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!