feat: implement automatic cycle generation for members

- Add CycleGenerator module with advisory lock mechanism
- Add SetMembershipFeeStartDate change for auto-calculation
- Extend Settings with include_joining_cycle and default_membership_fee_type_id
- Add scheduled job skeleton for future Oban integration

priv/repo/migrations/20251211195058_add_membership_fee_settings.exs

@@ -0,0 +1,25 @@
+defmodule Mv.Repo.Migrations.AddMembershipFeeSettings do
+  @moduledoc """
+  Adds membership fee settings to the settings table.
+
+  Note: The members table columns (membership_fee_start_date, membership_fee_type_id)
+  were already added in migration 20251211151449_add_membership_fees_tables.
+  """
+
+  use Ecto.Migration
+
+  def up do
+    # Add membership fee settings to the settings table
+    alter table(:settings) do
+      add_if_not_exists :include_joining_cycle, :boolean, null: false, default: true
+      add_if_not_exists :default_membership_fee_type_id, :uuid
+    end
+  end
+
+  def down do
+    alter table(:settings) do
+      remove_if_exists :default_membership_fee_type_id, :uuid
+      remove_if_exists :include_joining_cycle, :boolean
+    end
+  end
+end