Plan page presentation is now editable from Admin → Settings → Billing & purchases.

Editable:
- Plan page eyebrow, title and description
- Free/Pro/Pro Plus display names
- Plan descriptions
- Feature lists (one feature per line)
- Free footer message
- Pro web purchase button label
- Pro Android purchase note
- Pro Plus monthly/yearly subscription button labels
- Existing pricing and Stripe/Google Play billing fields remain editable

Not editable from marketing settings:
- The actual entitlement/capability rules for Free, Pro and Pro Plus.
  Those remain enforced in Symfony code for security and consistency.

No database migration is required because these values use the existing application_setting table.
This update does not include or modify .env.