Add PHP 8.4 and PHP 8.5 compatibility

[SamueleMartini]

Summary

This PR adds PHP 8.4 and PHP 8.5 compatibility to MageOS_ThemeOptimization while keeping the module working on PHP 8.1/8.2/8.3.

Current last tag: 2.2.0. Suggested next tag: 2.3.0 (backwards-compatible additions/changes only).

cc @rhoerr

Changes

• Added declare(strict_types=1) to every PHP class in the module (previously missing on ViewTransitions, SpeculationRules, UpdateSpeculationRulesConfigPathPatch).
• Added explicit return types to every method, including Setup\Patch\Data\UpdateSpeculationRulesConfigPathPatch::apply(), getAliases() and getDependencies(), so subclasses and static analysis don't fall back on the implicit-nullable/void deprecations introduced in PHP 8.4.
• Typed class constants (const string, const array) on ViewTransitions, SpeculationRules, BfCache and the Http plugin to take advantage of PHP 8.3+ typed constants.
• Typed nullable parameters explicitly (e.g. int|string|null $store in Http::getConfig()) so PHP 8.4's "implicit nullable parameter is deprecated" warning doesn't trigger.
• afterSetNoCacheHeaders now uses mixed $result / mixed return type instead of an untyped parameter.
• Replaced strpos($theme->getCode(), 'Hyva/') === 0 with str_starts_with() in SpeculationRules::isHyva().
• Constructor-promoted properties are now protected (instead of private) on every class, and private helpers (isHyva, isRequestCacheable, isRequestInExcludePatterns, parseExcludePatterns, isEnabled, getConfig) are also protected, so downstream modules/themes can extend the behavior without plugins.
• Minor refactors: array_map in place of manual foreach-and-append loops in SpeculationRules::getExcludedExtensions() / getExcludedSelectors(); unset($pattern) after the foreach-by-reference loop in getExcludedPaths(); re-imported Magento\Framework\App\Response\Http as ResponseHttp in the plugin so the fully-qualified-name isn't repeated in method signatures.
• composer.json: added an explicit php constraint ~8.1.0 || ~8.2.0 || ~8.3.0 || ~8.4.0 || ~8.5.0.
• Added a CHANGELOG.md with a 2.3.0 — 2026-04-21 entry.

Backwards compatibility

• No public method signature was changed; only return types were added where previously missing (always matching the documented @return).
• DataPatchInterface::apply() doesn't declare a return type in Magento framework (its PHPDoc says @return $this); the concrete apply() now declares : self and return $this, which is covariance-compatible with the interface.
• Visibility changes are widening only (private -> protected), so no downstream break.

Test plan

• composer install and module registration on PHP 8.1, 8.3, 8.4 and 8.5.
• Run the included unit tests (vendor/bin/phpunit Test/Unit) on PHP 8.4 and 8.5.
• Smoke test in a Magento 2.4.7+ storefront: speculation rules JSON is emitted, view-transitions CSS/JS is rendered, bfcache plugin flips no-store on cacheable responses.
• Verify no deprecation notices are raised with error_reporting(E_ALL) on PHP 8.4 / 8.5.

Suggested release

Tag 2.3.0 (minor bump — only additive/internal changes, no public API break).