feat(web): dashboard session deletion and E2E coverage for issue #150

- Add DeleteSessionAsync to ISessionStore/SessionService (unpublish portfolio card,
  remove bot-created empty forum topic, update batch message).
- Add DeleteSessionForCurrentUserAsync to AuthorizedSessionService with audit log.
- Add delete button + confirmation dialog to GroupDetails.razor.
- Extend dashboard Playwright tests with edit persistence and delete verification.
- Update AuthorizedSessionServiceTests with delete authorization coverage.
- Mark issue #150 as done in tests/e2e/README.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/GmRelay.Web/Components/Pages/GroupDetails.razor

@@ -10,6 +10,7 @@
 @inject AuthorizedMembershipService MembershipService
 @inject AuthenticationStateProvider AuthStateProvider
 @inject NavigationManager Navigation
+@inject IJSRuntime JS
 
 <PageTitle>Сессии группы — GM-Relay</PageTitle>
 
@@ -393,6 +394,9 @@
                                         ✏️ Изменить
                                     </a>
                                     <a href="/session/@session.Id/history" class="btn-gm btn-gm-outline">📜 История</a>
+                                    <button type="button" class="btn-gm btn-gm-danger" disabled="@(deletingSessionId == session.Id)" @onclick="() => DeleteSession(session.Id, session.Title)">
+                                        @(deletingSessionId == session.Id ? "⏳ Удаляем..." : "🗑 Удалить")
+                                    </button>
                                     @if (CanPromote(session))
                                     {
                                         <button type="button" class="btn-gm btn-gm-success" disabled="@(promotingSessionId == session.Id)" @onclick="() => PromoteWaitlisted(session.Id)">
@@ -491,6 +495,9 @@
                             ✏️ Изменить
                         </a>
                         <a href="/session/@session.Id/history" class="btn-gm btn-gm-outline" style="flex: 1; justify-content: center; font-size: 0.8125rem; padding: 0.5rem;">📜 История</a>
+                        <button type="button" class="btn-gm btn-gm-danger" style="flex: 1; justify-content: center; font-size: 0.8125rem; padding: 0.5rem;" disabled="@(deletingSessionId == session.Id)" @onclick="() => DeleteSession(session.Id, session.Title)">
+                            @(deletingSessionId == session.Id ? "⏳ Удаляем..." : "🗑 Удалить")
+                        </button>
                         @if (CanPromote(session))
                         {
                             <button type="button" class="btn-gm btn-gm-success" style="flex: 1; justify-content: center; font-size: 0.8125rem; padding: 0.5rem;" disabled="@(promotingSessionId == session.Id)" @onclick="() => PromoteWaitlisted(session.Id)">
@@ -572,6 +579,7 @@
     private HashSet<Guid> expandedSessions = new();
     private Guid? kickingParticipantId;
     private Guid? loadingParticipantsSessionId;
+    private Guid? deletingSessionId;
 
     protected override async Task OnInitializedAsync()
     {
@@ -904,6 +912,40 @@
         }
     }
 
+    private async Task DeleteSession(Guid sessionId, string title)
+    {
+        var confirmed = await JS.InvokeAsync<bool>("confirm", $"Удалить сессию «{title}»?");
+        if (!confirmed)
+        {
+            return;
+        }
+
+        errorMessage = null;
+        successMessage = null;
+        deletingSessionId = sessionId;
+
+        try
+        {
+            await SessionService.DeleteSessionForCurrentUserAsync(sessionId);
+            expandedSessions.Remove(sessionId);
+            participantsCache.Remove(sessionId);
+            successMessage = "Сессия удалена.";
+            await LoadSessions();
+        }
+        catch (SessionAccessDeniedException)
+        {
+            Navigation.NavigateTo("/access-denied");
+        }
+        catch (Exception ex)
+        {
+            errorMessage = ex.Message;
+        }
+        finally
+        {
+            deletingSessionId = null;
+        }
+    }
+
     private static string FormatParticipantUsername(WebParticipant p)
     {
         var username = string.IsNullOrWhiteSpace(p.TelegramUsername)

src/GmRelay.Web/Services/AuthorizedSessionService.cs

@@ -229,6 +229,22 @@ public sealed class AuthorizedSessionService(ISessionStore sessionStore, IHttpCo
             await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "MaxPlayers", session.MaxPlayers?.ToString(), maxPlayers?.ToString());
     }
 
+    public async Task DeleteSessionForCurrentUserAsync(Guid sessionId)
+    {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var session = await GetSessionForCurrentUserAsync(sessionId);
+        if (session is null)
+        {
+            throw new SessionAccessDeniedException(sessionId, identity.Value.ExternalUserId);
+        }
+
+        var title = await sessionStore.DeleteSessionAsync(sessionId, session.GroupId);
+        await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "Deleted", title, null);
+    }
+
     public async Task PromoteWaitlistedPlayerForCurrentUserAsync(Guid sessionId)
     {
         var identity = GetCurrentIdentity();

src/GmRelay.Web/Services/ISessionStore.cs

@@ -150,6 +150,7 @@ public interface ISessionStore
     Task<List<PlayerAttendanceStats>> GetGroupAttendanceStatsAsync(Guid groupId);
     Task LogSessionChangeAsync(Guid sessionId, string actorExternalUserId, string actorName, string changeType, string? oldValue, string? newValue);
     Task<List<SessionAuditLogEntry>> GetSessionHistoryAsync(Guid sessionId);
+    Task<string?> DeleteSessionAsync(Guid sessionId, Guid groupId);
     Task UpsertDiscordUserAsync(string discordId, string displayName, string? avatarUrl);
     Task<MasterProfileSettings?> GetMasterProfileSettingsAsync(string platform, string externalUserId);
     Task UpdateMasterProfileSettingsAsync(string platform, string externalUserId, string? publicSlug, bool isPublic, string displayName, string? bio);

src/GmRelay.Web/Services/SessionService.cs

@@ -129,6 +129,14 @@ internal sealed record WebBatchSessionRow(
     string? CoverImageUrl = null);
 internal sealed record WebTemplateGroupDto(long TelegramChatId);
 internal sealed record WebTemplateTopicDestination(int? MessageThreadId, bool TopicCreatedByBot);
+internal sealed record WebDeleteSessionInfo(
+    Guid Id,
+    string Title,
+    Guid BatchId,
+    long TelegramChatId,
+    int? BatchMessageId,
+    int? ThreadId,
+    bool TopicCreatedByBot);
 internal sealed record WebPublicGroupRow(
     Guid GroupId,
     string Name,
@@ -1086,6 +1094,95 @@ public sealed class SessionService(
         }
     }
 
+    public async Task<string?> DeleteSessionAsync(Guid sessionId, Guid groupId)
+    {
+        await using var conn = await dataSource.OpenConnectionAsync();
+        await using var transaction = await conn.BeginTransactionAsync();
+
+        var session = await conn.QuerySingleOrDefaultAsync<WebDeleteSessionInfo>(
+            """
+            SELECT s.id AS Id,
+                   s.title AS Title,
+                   s.batch_id AS BatchId,
+                   g.external_group_id::BIGINT AS TelegramChatId,
+                   s.batch_message_id AS BatchMessageId,
+                   s.thread_id AS ThreadId,
+                   s.topic_created_by_bot AS TopicCreatedByBot
+            FROM sessions s
+            JOIN game_groups g ON g.id = s.group_id
+            WHERE s.id = @SessionId AND s.group_id = @GroupId
+            FOR UPDATE
+            """,
+            new { SessionId = sessionId, GroupId = groupId },
+            transaction);
+
+        if (session is null)
+        {
+            throw new SessionAccessDeniedException(sessionId, "0");
+        }
+
+        await conn.ExecuteAsync(
+            """
+            UPDATE portfolio_games pg
+            SET is_public = false,
+                updated_at = now()
+            FROM portfolio_game_sessions pgs
+            WHERE pgs.portfolio_game_id = pg.id
+              AND pgs.session_id = @SessionId
+              AND pg.is_public = true
+            """,
+            new { SessionId = sessionId },
+            transaction);
+
+        await conn.ExecuteAsync(
+            "DELETE FROM sessions WHERE id = @Id AND group_id = @GroupId",
+            new { Id = sessionId, GroupId = groupId },
+            transaction);
+
+        var remainingInTopic = session.ThreadId.HasValue
+            ? await conn.ExecuteScalarAsync<int>(
+                """
+                SELECT COUNT(*)
+                FROM sessions
+                WHERE group_id = @GroupId
+                  AND thread_id = @ThreadId
+                """,
+                new { GroupId = groupId, ThreadId = session.ThreadId.Value },
+                transaction)
+            : 0;
+
+        await transaction.CommitAsync();
+
+        if (session.ThreadId.HasValue && session.TopicCreatedByBot && remainingInTopic == 0)
+        {
+            try
+            {
+                await bot.DeleteForumTopic(
+                    chatId: session.TelegramChatId,
+                    messageThreadId: session.ThreadId.Value);
+                logger.LogInformation(
+                    "Deleted forum topic {ThreadId} for group {GroupId} as no sessions remained.",
+                    session.ThreadId.Value,
+                    groupId);
+            }
+            catch (Exception ex)
+            {
+                logger.LogWarning(
+                    ex,
+                    "Failed to delete forum topic {ThreadId} for group {GroupId}",
+                    session.ThreadId.Value,
+                    groupId);
+            }
+        }
+
+        if (session.BatchMessageId.HasValue)
+        {
+            await TryUpdateBatchMessageAsync(session.BatchId, session.TelegramChatId, session.BatchMessageId.Value, session.Title);
+        }
+
+        return session.Title;
+    }
+
     public async Task PromoteWaitlistedPlayerAsync(Guid sessionId, Guid groupId)
     {
         await using var conn = await dataSource.OpenConnectionAsync();