Applies #12868 - fixes EOL date on asset creation

[snipe]

This just applies PR #12868 to develop. There were a lot of unnecessary (more recent) changes that didn't belong in there, so this just seemed easier.

[what-the-diff]

PR Summary

• Mandatory purchase_cost field
  The purchase_cost field is now required for both the API and web interface, ensuring accurate cost tracking.
• Default asset EOL date
  If no asset end-of-life (EOL) date is provided, a default value will be set based on warranty months or manufacturer's suggested EOL, improving lifecycle management.