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/GmRelay.E2E.Runner.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <LangVersion>preview</LangVersion>
+    <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="WTelegramClient" Version="4.3.5" />
+    <PackageReference Include="dotenv.net" Version="3.2.1" />
+  </ItemGroup>
+
+</Project>