feat(e2e): #146 MTProto Telegram user client runner

- Add standalone C# console runner tests/e2e/runner/ using WTelegramClient
- Provide TelegramUserClient wrapper: login, create supergroup, invite bot,
  send messages/commands, read recent messages, wait for bot reply
- Add .env.example and runner .gitignore to keep secrets/session files out of git
- Update E2E README with runner instructions and status table
- Runner project intentionally excluded from GM-Relay.slnx to avoid CI/AOT impact

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

tests/e2e/runner/Program.cs

@@ -0,0 +1,27 @@
+using dotenv.net;
+using GmRelay.E2E.Runner;
+
+DotEnv.Load(new DotEnvOptions(envFilePaths: [".env"], ignoreExceptions: false));
+
+var config = new RunnerConfig
+{
+    ApiId = int.Parse(Environment.GetEnvironmentVariable("api_id")!),
+    ApiHash = Environment.GetEnvironmentVariable("api_hash")!,
+    PhoneNumber = Environment.GetEnvironmentVariable("phone_number")!,
+    BotUsername = Environment.GetEnvironmentVariable("TELEGRAM_BOT_USERNAME")!,
+    BotToken = Environment.GetEnvironmentVariable("TELEGRAM_BOT_TOKEN")!,
+};
+
+using var runner = new TelegramUserClient(config);
+await runner.ConnectAsync();
+
+Console.WriteLine("Connected as Telegram user. Creating test group...");
+var group = await runner.CreateGroupAsync("GmRelay E2E Test Group");
+Console.WriteLine($"Created group id={group.Id} title='{group.Title}'");
+
+await runner.InviteBotToGroupAsync(group, config.BotUsername);
+Console.WriteLine($"Invited @{config.BotUsername} to the group");
+
+// Keep the process alive briefly so the session is persisted.
+await Task.Delay(TimeSpan.FromSeconds(2));
+Console.WriteLine("Done.");