fix: owner event bookings list and paid plan durations from plan_to_months.

Fixes EventHub/EventHubBack#51
Fixes EventHub/EventHubBack#52

Co-authored-by: Cursor <cursoragent@cursor.com>

test/unit/core_subscription_tests.erl

@@ -27,6 +27,10 @@ core_subscription_test_() ->
     [
       {"Create trial subscription", fun test_create_trial/0},
       {"Create paid subscription", fun test_create_paid/0},
+      {"Create monthly duration", fun test_create_monthly_duration/0},
+      {"Create quarterly duration", fun test_create_quarterly_duration/0},
+      {"Create biannual duration", fun test_create_biannual_duration/0},
+      {"Create annual duration", fun test_create_annual_duration/0},
       {"Get active by user", fun test_get_active_by_user/0},
       {"List by user", fun test_list_by_user/0},
       {"Update status", fun test_update_status/0},
@@ -51,6 +55,35 @@ test_create_paid() ->
   ?assertEqual(true, Sub#subscription.trial_used),
   ?assertEqual(active, Sub#subscription.status).
 
+%% Длительность не зависит от trial_used — только от Plan (месяц ≈ 30 дней).
+%% add_months считает по календарным дням от полуночи даты старта.
+assert_plan_duration(Sub, Months) ->
+  {{Y1, M1, D1}, _} = Sub#subscription.started_at,
+  {{Y2, M2, D2}, Time2} = Sub#subscription.expires_at,
+  StartDays = calendar:date_to_gregorian_days({Y1, M1, D1}),
+  EndDays = calendar:date_to_gregorian_days({Y2, M2, D2}),
+  ?assertEqual(Months * 30, EndDays - StartDays),
+  ?assertEqual({0, 0, 0}, Time2).
+
+test_create_monthly_duration() ->
+  %% Даже при trial_used=false длительность = 1 месяц, не «trial 30 дней» отдельно
+  {ok, Sub} = core_subscription:create(<<"u-m">>, monthly, false),
+  ?assertEqual(false, Sub#subscription.trial_used),
+  assert_plan_duration(Sub, 1).
+
+test_create_quarterly_duration() ->
+  {ok, Sub} = core_subscription:create(<<"u-q">>, quarterly, false),
+  ?assertEqual(false, Sub#subscription.trial_used),
+  assert_plan_duration(Sub, 3).
+
+test_create_biannual_duration() ->
+  {ok, Sub} = core_subscription:create(<<"u-b">>, biannual, true),
+  assert_plan_duration(Sub, 6).
+
+test_create_annual_duration() ->
+  {ok, Sub} = core_subscription:create(<<"u-a">>, annual, false),
+  assert_plan_duration(Sub, 12).
+
 test_get_active_by_user() ->
   UserId = <<"user123">>,
   {ok, Sub1} = core_subscription:create(UserId, trial, false),