refactor: add platform messenger contracts

Introduce platform-neutral PlatformKind, PlatformUser, PlatformGroup, and IPlatformMessenger contracts in GmRelay.Shared.

Route Telegram session schedule updates, direct notifications, interaction replies, and calendar export through TelegramPlatformMessenger while preserving existing Telegram behavior.

Bump version -> 2.0.1

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

@@ -2,6 +2,7 @@ using Dapper;
 using GmRelay.Bot.Features.Notifications;
 using GmRelay.Bot.Infrastructure.Scheduling;
 using GmRelay.Shared.Domain;
+using GmRelay.Shared.Platform;
 using GmRelay.Shared.Rendering;
 using Npgsql;
 using Telegram.Bot;
@@ -26,6 +27,7 @@ internal sealed record DueRescheduleProposalDto(
 public sealed class RescheduleVotingDeadlineService(
     NpgsqlDataSource dataSource,
     ITelegramBotClient bot,
+    IPlatformMessenger messenger,
     DirectSessionNotificationSender directSender,
     ISystemClock clock,
     ILogger<RescheduleVotingDeadlineService> logger) : BackgroundService
@@ -312,24 +314,20 @@ public sealed class RescheduleVotingDeadlineService(
             if (proposal.BatchMessageId.HasValue)
             {
                 var view = SessionBatchViewBuilder.Build(proposal.Title, batchSessions, batchParticipants);
-                var renderResult = TelegramSessionBatchRenderer.Render(view);
 
-                await BatchMessageEditor.EditBatchMessageAsync(
-                    bot,
-                    chatId: proposal.TelegramChatId,
-                    messageId: proposal.BatchMessageId.Value,
-                    text: renderResult.Text,
-                    replyMarkup: renderResult.Markup,
+                await messenger.UpdateScheduleAsync(
+                    new PlatformScheduleMessage(
+                        TelegramPlatformIds.Group(proposal.TelegramChatId, proposal.ThreadId),
+                        view,
+                        TelegramPlatformIds.Message(proposal.TelegramChatId, proposal.ThreadId, proposal.BatchMessageId.Value)),
                     ct);
             }
             else
             {
-                await bot.SendMessage(
-                    chatId: proposal.TelegramChatId,
-                    messageThreadId: proposal.ThreadId,
-                    text: $"📣 Расписание обновлено после голосования за перенос сессии «{System.Net.WebUtility.HtmlEncode(proposal.Title)}».",
-                    parseMode: ParseMode.Html,
-                    cancellationToken: ct);
+                await messenger.SendGroupMessageAsync(
+                    TelegramPlatformIds.Group(proposal.TelegramChatId, proposal.ThreadId),
+                    $"📣 Расписание обновлено после голосования за перенос сессии «{System.Net.WebUtility.HtmlEncode(proposal.Title)}».",
+                    ct);
             }
         }
         catch (Exception ex)