Subscription IsCustom

[GAlexIHU]

Overview

• Storing the timestamp of the last edit on the subscription
• Adding IsCustom field: if a subscription doesn't have a plan ref (created as a custom sub) or is edited (has edit timestamp) it will be a custom subscription.
• We don't try to guess last edit times for existing subscriptions: for existing subs, they'll only be custom if they dont have a planref

Summary by CodeRabbit

• New Features
  • Subscriptions now show a “custom” indicator to reveal whether they were customized.
  • A “last edited” timestamp has been added to subscription details, offering better visibility into recent modifications.
  • Updates to subscription editing now validate that customizations are provided, ensuring users receive clear error feedback when input is missing.