feat: implement payout system database schema and models

app/models/earning.rb

@@ -0,0 +1,16 @@
+class Earning < ApplicationRecord
+  # === Relations ===
+  belongs_to :event
+  belongs_to :user
+  belongs_to :order
+
+  # === Enums ===
+  enum :status, { pending: 0, paid: 1 }
+
+  # === Validations ===
+  validates :amount_cents, presence: true, numericality: { greater_than_or_equal_to: 0 }
+  validates :fee_cents, presence: true, numericality: { greater_than_or_equal_to: 0 }
+  validates :net_amount_cents, numericality: { greater_than_or_equal_to: 0, allow_nil: true }
+  validates :status, presence: true
+  validates :stripe_payout_id, allow_blank: true, uniqueness: true
+end