feat: HuggingFace Hub Scanner - Spaces und Models nach API-Keys durchsuchen

- Neue ScanHuggingFace()-Methode: durchsucht Spaces und Models
- 6 Suchbegriffe (anthropic, claude, openai, api-key, chatgpt, gpt4)
- Rekursive Dateiliste, filtert nach relevanten Extensions
- Limits: 50 Dateien/Repo, 500KB/Datei, 300ms Delay
- Läuft in Web- und Full-Mode (nicht Quick)
- Optionales HuggingFaceToken-Setting für höhere Rate-Limits
- CSS: font-size Bereinigung in chat.css

Services/ServerSettingsService.cs

@@ -35,6 +35,7 @@ public class ServerSettingsService
         new SettingDefinition( "SerperApiKey",       "string", "",      "Serper.dev API-Key für Google-Suche (Key-Scanner + Tool)",       "password" ),
         new SettingDefinition( "ScanIntervalHours",  "int",    "0",     "Key-Scanner Intervall in Stunden (0 = nur manuell)",             "number"   ),
         new SettingDefinition( "GitHubEventScanner", "bool",   "false", "GitHub Event Scanner (Echtzeit-Monitoring öffentlicher Pushes)", "toggle"   ),
+        new SettingDefinition( "HuggingFaceToken",   "string", "",      "HuggingFace Token (optional, erhöht Rate-Limits)",            "password" ),
         new SettingDefinition( "ScannerKeyTypes",    "string_array", "anthropic_oauth,krea_ai", "Key-Scanner: Aktive Key-Typen",                               "checkboxes" ),
     };