Referral feature: Database

[qisforq]

Objective:

Modify the database schema to support the Invite a Friend feature by extending existing tables and creating a new table for invitations.

Sub-tasks:

1. Extend the player_cards_images table to include an 'owner' field, which will store the user_id of the user who owns the card.
2. Create the invitations table with the following fields:
   • invite_id (primary key, unique identifier)
   • guest_email (text field for the email of the invited guest)
   • card (foreign key linking to the card_id in the player_cards_images table)
   • status (custom enum type with values 'pending', 'accepted', and 'revoked')
   • guest (foreign key linking to the user_id in the users table for the invited guest)
   • created_at (optional timestamp for when the invite was created)
   • accepted_at (optional timestamp for when the invite was accepted)
   • revoked_at (optional timestamp for when the invite was revoked)
3. Optionally extend the users table to include a created_at timestamp.