Add disablePackageReplace() and disableAutoloadMerge() opt-outs for non-library monorepos

[kayw-geek]

Summary

Two opt-in switches on MBConfig for monorepos that are not published as a library (e.g. Laravel apps using path repos + self.version requires):

• MBConfig::disablePackageReplace() — skip ReplaceSectionJsonDecorator. The default replace: { internal/pkg: self.version } makes Composer treat the root as already providing internal packages → they're never installed → never appear in vendor/composer/installed.json → Laravel's package auto-discovery breaks. Opting out fixes this.
• MBConfig::disableAutoloadMerge() — skip merging autoload / autoload-dev from package composer.json into root. With replace disabled, internal packages get installed via path repos and bring their own autoload, so the merged root entries become redundant (duplicate PSR-4 mappings).

Both follow the existing static-flag pattern of MBConfig::disableDefaultWorkers(). Default behavior unchanged.

Usage

return static function (MBConfig $mbConfig): void {
    MBConfig::disablePackageReplace();
    MBConfig::disableAutoloadMerge();
};

Test plan

• New unit tests cover default + disabled paths for replace section, autoload merge, and autoload-dev merge
• Full suite green (67/275)
• composer check-cs, composer check-rector, phpstan clean