Refactor: Server-Settings von appsettings.json in DB-Tabelle (server_settings)

- Neuer ServerSettingsService: zentrale Settings in SQLite mit In-Memory-Cache
- Auto-Migration: bestehende appsettings.Production.json wird einmalig in DB übernommen
- Alle Services umgestellt: IConfiguration → ServerSettingsService (dynamisch, kein Neustart)
- Port bleibt als einziges Setting in appsettings.Production.json (erfordert Neustart)
- ServerSettingsEndpoint: liest/schreibt DB statt JSON-Datei, Port als Sonder-Setting
- IConfiguration komplett entfernt aus allen Services (ChatService, ToolService, AnthropicService,
  OpenAiService, KreaService, TelegramService, KeyScannerService, GitHubEventScannerService)
- AuthMiddleware: KreaApiKey dynamisch aus DB
- appsettings.json bereinigt: nur noch Port und Logging
- Dokumentation aktualisiert (ARCHITECTURE.md, ARCHITECTURE_QUICK.md, README.md)

Services/GitHubEventScannerService.cs

@@ -8,7 +8,6 @@ using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using Gott.Models;
-using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 
@@ -23,8 +22,10 @@ public class GitHubEventScannerService : BackgroundService
     private readonly DatabaseService _db;
     private readonly IHttpClientFactory _httpFactory;
     private readonly ILogger<GitHubEventScannerService> _logger;
-    private readonly string _githubToken;
-    private readonly bool _enabled;
+    private readonly ServerSettingsService _settings;
+
+    private string _githubToken => _settings.Get("GitHubToken");
+    private bool _enabled => _settings.GetBool("GitHubEventScanner", false);
 
     private const int PollIntervalMs = 30_000;       // 30 Sekunden (häufiger pollen, weniger verpassen)
     private const int MaxCommitsPerPoll = 30;         // Max Commit-Diffs pro Poll-Zyklus
@@ -90,31 +91,18 @@ public class GitHubEventScannerService : BackgroundService
     public GitHubEventScannerService(
         DatabaseService db,
         IHttpClientFactory httpFactory,
-        IConfiguration config,
+        ServerSettingsService settings,
         ILogger<GitHubEventScannerService> logger)
     {
         _db = db;
         _httpFactory = httpFactory;
+        _settings = settings;
         _logger = logger;
-        _githubToken = config["GitHubToken"] ?? "";
-        _enabled = config.GetValue<bool>("GitHubEventScanner", false);
     }
 
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
-        if (!_enabled)
-        {
-            _logger.LogInformation("GitHubEventScannerService deaktiviert (GitHubEventScanner=false)");
-            return;
-        }
-
-        if (string.IsNullOrWhiteSpace(_githubToken))
-        {
-            _logger.LogWarning("GitHubEventScannerService deaktiviert (kein GitHubToken konfiguriert)");
-            return;
-        }
-
-        _logger.LogInformation("GitHubEventScannerService gestartet (Poll-Intervall: {Interval}s)", PollIntervalMs / 1000);
+        _logger.LogInformation("GitHubEventScannerService bereit (Enabled wird dynamisch aus Settings gelesen)");
 
         // Kurze Verzögerung nach App-Start
         await Task.Delay(5_000, stoppingToken);
@@ -123,6 +111,13 @@ public class GitHubEventScannerService : BackgroundService
 
         while (!stoppingToken.IsCancellationRequested)
         {
+            // Dynamisch prüfen ob aktiviert
+            if (!_enabled || string.IsNullOrWhiteSpace(_githubToken))
+            {
+                lock (_lock) _isRunning = false;
+                await Task.Delay(10_000, stoppingToken);
+                continue;
+            }
             try
             {
                 lock (_lock) _isRunning = true;