Add Vorlagen editor, upload portal, onboarding, and participant import command

- Dokument-Vorlagen-Editor: create/edit/reset document templates (admin)
- Upload-Portal: public portal for Nachweis uploads via token
- Onboarding: invite Destinatäre via email with multi-step wizard
- Bestätigungsschreiben: preview and send confirmation letters
- Email settings: SMTP configuration UI
- Management command: import_veranstaltung_teilnehmer for bulk participant import

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/stiftung/management/commands/init_config.py

@@ -69,6 +69,67 @@ class Command(BaseCommand):
                 "category": "email",
                 "order": 6,
             },
+            # SMTP Settings
+            {
+                "key": "smtp_host",
+                "display_name": "SMTP Server",
+                "description": "Hostname des SMTP-Servers (z.B. smtp.ionos.de)",
+                "value": "smtp.ionos.de",
+                "default_value": "smtp.ionos.de",
+                "setting_type": "text",
+                "category": "email",
+                "order": 10,
+            },
+            {
+                "key": "smtp_port",
+                "display_name": "SMTP Port",
+                "description": "Port des SMTP-Servers (465 für SSL, 587 für STARTTLS)",
+                "value": "465",
+                "default_value": "465",
+                "setting_type": "number",
+                "category": "email",
+                "order": 11,
+            },
+            {
+                "key": "smtp_user",
+                "display_name": "SMTP Benutzername",
+                "description": "Benutzername / E-Mail-Adresse für die SMTP-Anmeldung",
+                "value": "",
+                "default_value": "",
+                "setting_type": "text",
+                "category": "email",
+                "order": 12,
+            },
+            {
+                "key": "smtp_password",
+                "display_name": "SMTP Passwort",
+                "description": "Passwort für die SMTP-Anmeldung",
+                "value": "",
+                "default_value": "",
+                "setting_type": "password",
+                "category": "email",
+                "order": 13,
+            },
+            {
+                "key": "smtp_use_ssl",
+                "display_name": "SSL/TLS verwenden (SMTP)",
+                "description": "Sichere Verbindung zum SMTP-Server (empfohlen für Port 465)",
+                "value": "True",
+                "default_value": "True",
+                "setting_type": "boolean",
+                "category": "email",
+                "order": 14,
+            },
+            {
+                "key": "smtp_from_email",
+                "display_name": "Absenderadresse (SMTP)",
+                "description": "Absenderadresse für ausgehende E-Mails (z.B. buero@vhtv-stiftung.de)",
+                "value": "buero@vhtv-stiftung.de",
+                "default_value": "buero@vhtv-stiftung.de",
+                "setting_type": "text",
+                "category": "email",
+                "order": 15,
+            },
         ]
 
         all_settings = email_settings