Add Laravel 13 support and migrate to PHPStan 2

[soymgomez]

Summary

Adds Laravel 13 compatibility, ensures the package works on PHP 8.3 and 8.4, and migrates static analysis to PHPStan 2.

Dependencies (composer.json)

• illuminate/macroable: ^11.0|^12.0 → ^11.0|^12.0|^13.0 (Laravel 13)
• phpunit/phpunit: ^10.0|^11.0 → ^10.0|^11.0|^12.0 (Laravel 13 projects commonly use PHPUnit 12)
• phpstan/phpstan: ^1.8 → ^2.0
• php kept at ^8.2; symfony/dom-crawler kept at ^6.1|^7.0

CI

• Added 12.* to the PHPUnit matrix in run-tests.yml, excluding PHP 8.2 + PHPUnit 12 (PHPUnit 12 requires PHP ≥ 8.3).

PHPStan 2 migration

Fixed the two stricter findings in code (no baseline added):

• Robots.php — the array<Robots::*> PHPDoc claimed no falsy values, flagging array_filter as a no-op. The real type from explode() is array<string> (empty strings the filter legitimately removes).
• HTMLParser.php — removed a now-unnecessary @phpstan-ignore; tightening the param PHPDoc to string|array<string>|null lets the template resolve cleanly.

Decisions

• PHP min stays ^8.2: the package only depends on illuminate/macroable (not the full framework), so it keeps Laravel 11/12 + PHP 8.2 compatibility. Laravel 13 already enforces PHP 8.3 via its own constraint.
• symfony/dom-crawler not bumped to ^8.0: v8 is beta and requires PHP ≥ 8.4.1, which would break PHP 8.3. ^7.0 already works with Laravel 13.
• Larastan not added: the code uses no Laravel-specific features (Eloquent, facades, container) — only DomCrawler and the Macroable trait — so it would add no value while pulling in heavy dependencies.

Verification

Locally on PHP 8.3: PHPStan 2 reports no errors, Pint passes, and all 32 tests (118 assertions) pass against illuminate/macroable v13 + PHPUnit 12.