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

config/test.exs

@@ -48,3 +48,6 @@ config :mv, :require_token_presence_for_authentication, false
 
 # Enable SQL Sandbox for async LiveView tests
 config :mv, :sql_sandbox, true
+
+# Mark test environment for conditional behavior (e.g., sync vs async operations)
+config :mv, :env, :test