Fix server limit for product upgrades/downgrades

[KroZen-Dev]

Description

Fixed server limit feature for product upgrades/downgrades. When a product has a serverlimit set (non-zero), users was able upgrade/downgrade to the product that already reached its limit for user.

Changes:

• Added server limit validation when listing available upgrade products
• Added server limit validation when upgrading a server to a different product
• Added server limit validation in the validateUpgrade method

Type of Change

• Bug fix

Testing

• Tested creating a server when product limit is reached (should show error)
• Tested upgrading to a product that has reached its limit (should show error)
• Tested that products with serverlimit = 0 (unlimited) work as before
• Tested that upgrading to the same product doesn't trigger limit check
• Verified upgrade product list correctly marks limited products as "doesNotFit"

AI Assistance

• I used AI tools to assist with this contribution

Checklist

• My PR targets the development branch
• Commit messages follow Conventional Commits
• I have reviewed my own code
• I have tested all affected functionality
• No new warnings or errors introduced

[MrWeez]

The limit-check logic is duplicated three times. Same block (count >= serverlimit && serverlimit != 0) is copy-pasted across getUpgradeOptions, upgrade(), and validateUpgrade(). On top of that, the check in upgrade() is effectively duplicated by the one inside validateUpgrade(), which upgrade() calls right afterward meaning the same COUNT query hits the DB twice within a single request. Worth extracting into a single private method, and reuse it everywhere (see example bellow), leaving upgrade() only responsible for returning its specific error message.

private function productLimitReached(User $user, Product $product): bool

[MrWeez]

Awesome!