Cronjobs + AnthropicService Singleton Refactoring

Cronjobs:
- CronjobService (BackgroundService) prüft jede Minute auf fällige Jobs
- Cron-Expression in Server-Lokalzeit via Cronos (CronFormat.Standard)
- Cronjob-Ausführung: Prompt → Session → Agent-Antwort in Chat-History
- Optionale Benachrichtigungs-Session (notify_session_id): Zusammenfassung
  wird in separate Session geschrieben (z.B. mit Telegram)
- Telegram-Benachrichtigung mit Cronjob-Name + Ursprungs-Session
- REST API: CRUD + toggle + manuelles Ausführen (/run)
- Frontend: Dashboard-Cards, Cronjob-Formular mit Cron-Vorschau,
  Session-Dropdown, Notify-Session-Dropdown, Status-Box

Refactoring:
- AnthropicService als Singleton in DI registriert
- ChatEndpoint + TelegramService nutzen injizierte Instanz
- Redundante Dependencies (Token, ToolService, MemoryService) entfernt

Neue Dateien:
- Models/CronjobRecord.cs
- Services/CronjobService.cs
- Endpoints/CronjobEndpoint.cs
- wwwroot/js/pages/cronjob-page.js
- PLAN-Cronjob.md

Services/TelegramService.cs

@@ -10,29 +10,23 @@ namespace Gott.Services;
 
 public class TelegramService
 {
-    private readonly string _anthropicToken;
     private readonly IHttpClientFactory _httpFactory;
     private readonly DatabaseService _db;
-    private readonly ToolService _toolService;
-    private readonly MemoryService _memoryService;
     private readonly ChatService _chatService;
+    private readonly AnthropicService _anthropic;
     private readonly int _maxIterations;
 
     public TelegramService(
-        string anthropicToken,
         IHttpClientFactory httpFactory,
         DatabaseService db,
-        ToolService toolService,
-        MemoryService memoryService,
         ChatService chatService,
+        AnthropicService anthropic,
         int maxIterations = 100)
     {
-        _anthropicToken = anthropicToken;
         _httpFactory = httpFactory;
         _db = db;
-        _toolService = toolService;
-        _memoryService = memoryService;
         _chatService = chatService;
+        _anthropic = anthropic;
         _maxIterations = maxIterations;
     }
 
@@ -165,8 +159,7 @@ public class TelegramService
             });
 
             // AnthropicService für Non-Streaming-Chat nutzen
-            var anthropic = new AnthropicService(_httpFactory, _anthropicToken, _toolService, _db, _memoryService);
-            var reply = await anthropic.ChatNonStreaming(ctx, history, onIteration: async (iteration) =>
+            var reply = await _anthropic.ChatNonStreaming(ctx, history, onIteration: async (iteration) =>
             {
                 if (iteration % 3 == 0)
                     await SendChatAction(chatId, botToken, "typing");