feat(membership-fees): add database schema and Ash domain structure

lib/membership_fees/membership_fees.ex

@@ -0,0 +1,42 @@
+defmodule Mv.MembershipFees do
+  @moduledoc """
+  Ash Domain for membership fee management.
+
+  ## Resources
+  - `MembershipFeeType` - Defines membership fee types with intervals and amounts
+  - `MembershipFeeCycle` - Individual membership fee cycles per member
+
+  ## Overview
+  This domain handles the complete membership fee lifecycle including:
+  - Fee type definitions (monthly, quarterly, half-yearly, yearly)
+  - Individual fee cycles for each member
+  - Payment status tracking (unpaid, paid, suspended)
+
+  ## Architecture Decisions
+  - `interval` field on MembershipFeeType is immutable after creation
+  - `cycle_end` is calculated, not stored (from cycle_start + interval)
+  - `amount` is stored per cycle for audit trail when prices change
+  """
+  use Ash.Domain,
+    extensions: [AshAdmin.Domain, AshPhoenix]
+
+  admin do
+    show? true
+  end
+
+  resources do
+    resource Mv.MembershipFees.MembershipFeeType do
+      define :create_membership_fee_type, action: :create
+      define :list_membership_fee_types, action: :read
+      define :update_membership_fee_type, action: :update
+      define :destroy_membership_fee_type, action: :destroy
+    end
+
+    resource Mv.MembershipFees.MembershipFeeCycle do
+      define :create_membership_fee_cycle, action: :create
+      define :list_membership_fee_cycles, action: :read
+      define :update_membership_fee_cycle, action: :update
+      define :destroy_membership_fee_cycle, action: :destroy
+    end
+  end
+end