feat: Telegram Bot Integration

- TelegramService: Non-Streaming Claude Chat mit Tool-Loop,
  Commands (/start, /link, /session, /new, /clear, /status, /unlink),
  Nachrichten-Splitting bei >4096 Zeichen, Typing-Indicator,
  History-Aufbau aus DB, Token-Usage-Tracking
- TelegramEndpoint: Webhook (POST, no-auth), Link-Code-Generierung
  (POST, auth), Webhook-Registrierung + Info (Admin)
- DatabaseService: telegram_links Tabelle mit Link-Code-Flow
  (6-stelliger Code, 5 Min Ablauf), GetUserSessions
- AuthMiddleware: /api/telegram/webhook von Auth ausgenommen
- Session-Verknüpfung via Link-Code (Web-UI generiert Code,
  Telegram /link CODE löst ein)
- TelegramLinkRecord Model

Program.cs

@@ -1,9 +1,11 @@
 using System;
 using System.IO;
+using System.Net.Http;
 using Gott.Endpoints;
 using Gott.Middleware;
 using Gott.Services;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -20,8 +22,21 @@ builder.Services.AddSingleton(dbService);
 builder.Services.AddSingleton(new ToolService());
 builder.Services.AddSingleton(new ImageService());
 builder.Services.AddSingleton(new StreamingTracker());
-builder.Services.AddSingleton(new MemoryService(dataDir));
-builder.Services.AddSingleton(new SkillService(dataDir));
+var memoryService = new MemoryService(dataDir);
+var skillService = new SkillService(dataDir);
+builder.Services.AddSingleton(memoryService);
+builder.Services.AddSingleton(skillService);
+
+// Telegram Bot (optional – nur wenn Token konfiguriert)
+var telegramToken = builder.Configuration["TelegramBotToken"] ?? "";
+var telegramSecret = builder.Configuration["TelegramWebhookSecret"] ?? Guid.NewGuid().ToString("N");
+var anthropicToken = builder.Configuration["AnthropicToken"] ?? "";
+builder.Services.AddSingleton<TelegramService>(sp =>
+    new TelegramService(
+        telegramToken, telegramSecret, anthropicToken,
+        sp.GetRequiredService<IHttpClientFactory>(),
+        dbService, new ToolService(), memoryService, skillService,
+        builder.Configuration.GetValue<int>("MaxIterations", 100)));
 
 var app = builder.Build();
 app.UseDefaultFiles();
@@ -38,5 +53,6 @@ app.MapInfoEndpoint();
 app.MapBackupEndpoint();
 app.MapSkillEndpoints();
 app.MapProfileEndpoints();
+app.MapTelegramEndpoints();
 
 app.Run("http://0.0.0.0:19000");