feat(#20): довести RSVP и напоминания до полного набора событий

- Добавлена абстракция ISystemClock + SystemClock / FakeSystemClock
  для тестируемого scheduling.
- Добавлена миграция V014: confirmation_sent_at в sessions.
- Обновлен SendConfirmationHandler: записывает confirmation_sent_at.
- Обновлен SessionSchedulerService:
  - выделен ISessionTriggerStore / DbSessionTriggerStore
  - SQL-запросы используют параметр @Now вместо now()
  - добавлен публичный TickAsync для тестов
  - защита от дублей через confirmation_sent_at IS NULL
- Обновлен RescheduleVotingDeadlineService: использует ISystemClock.
- Добавлены интерфейсы ISendConfirmationHandler, ISendOneHourReminderHandler,
  ISendJoinLinkHandler для unit-тестируемости.
- Добавлены 8 unit-тестов SessionSchedulerService:
  - все 3 триггера (T-24h, T-1h, T-5min)
  - идемпотентность при повторном запуске
  - ошибки handler не падают и не блокируют другие сессии
  - ошибки store логируются без падения worker-а

Bump version -> 1.13.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/GmRelay.Bot/Features/Confirmation/SendConfirmation/ISendConfirmationHandler.cs

@@ -0,0 +1,6 @@
+namespace GmRelay.Bot.Features.Confirmation.SendConfirmation;
+
+public interface ISendConfirmationHandler
+{
+    Task HandleAsync(Guid sessionId, CancellationToken ct);
+}

src/GmRelay.Bot/Features/Confirmation/SendConfirmation/SendConfirmationHandler.cs

@@ -32,7 +32,7 @@ public sealed class SendConfirmationHandler(
     NpgsqlDataSource dataSource,
     ITelegramBotClient bot,
     DirectSessionNotificationSender directSender,
-    ILogger<SendConfirmationHandler> logger)
+    ILogger<SendConfirmationHandler> logger) : ISendConfirmationHandler
 {
     public async Task HandleAsync(Guid sessionId, CancellationToken ct)
     {
@@ -103,12 +103,13 @@ public sealed class SendConfirmationHandler(
             replyMarkup: keyboard,
             cancellationToken: ct);
 
-        // 5. Update session status and store message ID
+        // 5. Update session status, store message ID, and mark confirmation sent
         await connection.ExecuteAsync(
             """
             UPDATE sessions
             SET status = @Status,
                 confirmation_message_id = @MessageId,
+                confirmation_sent_at = now(),
                 updated_at = now()
             WHERE id = @SessionId
             """,

src/GmRelay.Bot/Features/Reminders/SendJoinLink/ISendJoinLinkHandler.cs

@@ -0,0 +1,6 @@
+namespace GmRelay.Bot.Features.Reminders.SendJoinLink;
+
+public interface ISendJoinLinkHandler
+{
+    Task HandleAsync(Guid sessionId, CancellationToken ct);
+}

src/GmRelay.Bot/Features/Reminders/SendJoinLink/SendJoinLinkHandler.cs

@@ -31,7 +31,7 @@ public sealed class SendJoinLinkHandler(
     NpgsqlDataSource dataSource,
     ITelegramBotClient bot,
     DirectSessionNotificationSender directSender,
-    ILogger<SendJoinLinkHandler> logger)
+    ILogger<SendJoinLinkHandler> logger) : ISendJoinLinkHandler
 {
     public async Task HandleAsync(Guid sessionId, CancellationToken ct)
     {

src/GmRelay.Bot/Features/Reminders/SendOneHourReminder/ISendOneHourReminderHandler.cs

@@ -0,0 +1,6 @@
+namespace GmRelay.Bot.Features.Reminders.SendOneHourReminder;
+
+public interface ISendOneHourReminderHandler
+{
+    Task HandleAsync(Guid sessionId, CancellationToken ct);
+}

src/GmRelay.Bot/Features/Reminders/SendOneHourReminder/SendOneHourReminderHandler.cs

@@ -15,7 +15,7 @@ internal sealed record OneHourReminderSession(
 public sealed class SendOneHourReminderHandler(
     NpgsqlDataSource dataSource,
     DirectSessionNotificationSender directSender,
-    ILogger<SendOneHourReminderHandler> logger)
+    ILogger<SendOneHourReminderHandler> logger) : ISendOneHourReminderHandler
 {
     public async Task HandleAsync(Guid sessionId, CancellationToken ct)
     {

src/GmRelay.Bot/Features/Sessions/RescheduleSession/RescheduleVotingDeadlineService.cs

@@ -1,5 +1,6 @@
 using Dapper;
 using GmRelay.Bot.Features.Notifications;
+using GmRelay.Bot.Infrastructure.Scheduling;
 using GmRelay.Shared.Domain;
 using GmRelay.Shared.Rendering;
 using Npgsql;
@@ -25,6 +26,7 @@ public sealed class RescheduleVotingDeadlineService(
     NpgsqlDataSource dataSource,
     ITelegramBotClient bot,
     DirectSessionNotificationSender directSender,
+    ISystemClock clock,
     ILogger<RescheduleVotingDeadlineService> logger) : BackgroundService
 {
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
@@ -55,10 +57,11 @@ public sealed class RescheduleVotingDeadlineService(
                 FROM reschedule_proposals
                 WHERE status = 'Voting'
                   AND voting_deadline_at IS NOT NULL
-                  AND voting_deadline_at <= now()
+                  AND voting_deadline_at <= @Now
                 ORDER BY voting_deadline_at
                 LIMIT 25
-                """)).ToList();
+                """,
+                new { Now = clock.UtcNow.UtcDateTime })).ToList();
 
             foreach (var proposalId in proposalIds)
             {
@@ -97,10 +100,10 @@ public sealed class RescheduleVotingDeadlineService(
             WHERE rp.id = @ProposalId
               AND rp.status = 'Voting'
               AND rp.voting_deadline_at IS NOT NULL
-              AND rp.voting_deadline_at <= now()
+              AND rp.voting_deadline_at <= @Now
             FOR UPDATE
             """,
-            new { ProposalId = proposalId },
+            new { ProposalId = proposalId, Now = clock.UtcNow.UtcDateTime },
             transaction);
 
         if (proposal is null)