feat(e2e): #147 group creation and bot invitation scenario

- Add GroupSetupScenario: create supergroup, invite GmRelay bot, send /start,
  wait for reply, then delete the group
- Extend TelegramUserClient with DeleteGroupAsync and channel cache
- Update Program.cs to run the scenario with cleanup in finally
- Update README status table and runner documentation

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

tests/e2e/runner/Program.cs

@@ -12,16 +12,29 @@ var config = new RunnerConfig
     BotToken = Environment.GetEnvironmentVariable("TELEGRAM_BOT_TOKEN")!,
 };
 
-using var runner = new TelegramUserClient(config);
-await runner.ConnectAsync();
+using var client = new TelegramUserClient(config);
+await client.ConnectAsync();
 
-Console.WriteLine("Connected as Telegram user. Creating test group...");
-var group = await runner.CreateGroupAsync("GmRelay E2E Test Group");
-Console.WriteLine($"Created group id={group.Id} title='{group.Title}'");
+var scenario = new GroupSetupScenario(client, config);
+ScenarioResult? result = null;
 
-await runner.InviteBotToGroupAsync(group, config.BotUsername);
-Console.WriteLine($"Invited @{config.BotUsername} to the group");
+try
+{
+    result = await scenario.RunAsync();
+    Console.WriteLine("Scenario completed successfully.");
+}
+catch (Exception ex)
+{
+    Console.WriteLine($"Scenario failed: {ex.Message}");
+    throw;
+}
+finally
+{
+    if (result is not null)
+    {
+        await scenario.CleanupAsync(result);
+    }
 
-// Keep the process alive briefly so the session is persisted.
-await Task.Delay(TimeSpan.FromSeconds(2));
-Console.WriteLine("Done.");
+    // Keep the session file written to disk.
+    await Task.Delay(TimeSpan.FromSeconds(2));
+}