Fix Verpachtungen list + migrate legacy pacht data to LandVerpachtung

- Add migrate_to_landverpachtung management command that converts
  old Land-level pacht fields (aktueller_paechter, pachtbeginn, etc.)
  into proper LandVerpachtung records
- Fix SyntaxError in system.py (fancy Unicode quotes in f-strings)
- Ran migration: 1 LandVerpachtung record created for Jens Bodden

The old system stored pacht data directly on the Land model.
The new LandVerpachtung model supports multiple leases per Land.
The verpachtung_list view queries LandVerpachtung, which was empty.

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

app/stiftung/management/commands/migrate_to_landverpachtung.py

@@ -0,0 +1,90 @@
+"""
+Migriert Legacy-Pachtdaten von Land-Feldern zu LandVerpachtung-Einträgen.
+
+Die alte Struktur speichert Pachtdaten direkt auf dem Land-Model
+(aktueller_paechter, pachtbeginn, pachtende, etc.).
+Die neue Struktur nutzt das LandVerpachtung-Model (1:n).
+"""
+
+from decimal import Decimal
+
+from django.core.management.base import BaseCommand
+from django.db import transaction
+
+from stiftung.models import Land, LandVerpachtung
+
+
+class Command(BaseCommand):
+    help = "Migriert Land-Pachtfelder zu LandVerpachtung-Einträgen"
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            "--dry-run",
+            action="store_true",
+            help="Zeigt nur an, was gemacht würde",
+        )
+
+    def handle(self, *args, **options):
+        dry_run = options["dry_run"]
+
+        lands = Land.objects.filter(
+            aktueller_paechter__isnull=False,
+        ).select_related("aktueller_paechter")
+
+        self.stdout.write(f"Land-Einträge mit aktueller_paechter: {lands.count()}")
+
+        created = 0
+        skipped = 0
+
+        with transaction.atomic():
+            for land in lands:
+                # Skip if LandVerpachtung already exists for this land+paechter
+                existing = LandVerpachtung.objects.filter(
+                    land=land, paechter=land.aktueller_paechter
+                ).exists()
+                if existing:
+                    self.stdout.write(
+                        self.style.WARNING(f"  Übersprungen: {land} (bereits migriert)")
+                    )
+                    skipped += 1
+                    continue
+
+                vertragsnummer = f"LEGACY-{land.lfd_nr}"
+                verpachtete_flaeche = land.verp_flaeche_aktuell or land.groesse_qm or Decimal("1.00")
+                pachtzins = land.pachtzins_pauschal or Decimal("0.00")
+
+                self.stdout.write(
+                    f"  Migriere: {land} -> {land.aktueller_paechter} "
+                    f"(Beginn={land.pachtbeginn}, Ende={land.pachtende}, "
+                    f"Fläche={verpachtete_flaeche}qm, Pachtzins={pachtzins}€)"
+                )
+
+                if not dry_run:
+                    LandVerpachtung.objects.create(
+                        land=land,
+                        paechter=land.aktueller_paechter,
+                        vertragsnummer=vertragsnummer,
+                        pachtbeginn=land.pachtbeginn or land.erstellt_am.date(),
+                        pachtende=land.pachtende,
+                        verlaengerung_klausel=land.verlaengerung_klausel,
+                        verpachtete_flaeche=verpachtete_flaeche,
+                        pachtzins_pauschal=pachtzins,
+                        pachtzins_pro_ha=land.pachtzins_pro_ha,
+                        zahlungsweise=land.zahlungsweise or "jaehrlich",
+                        ust_option=land.ust_option,
+                        ust_satz=land.ust_satz or Decimal("19.00"),
+                        grundsteuer_umlage=land.grundsteuer_umlage,
+                        versicherungen_umlage=land.versicherungen_umlage,
+                        verbandsbeitraege_umlage=land.verbandsbeitraege_umlage,
+                        jagdpacht_anteil_umlage=land.jagdpacht_anteil_umlage,
+                        status="aktiv",
+                        bemerkungen=f"Automatisch migriert aus Land-Feldern (Lfd.Nr. {land.lfd_nr})",
+                    )
+                    created += 1
+
+        action = "würden erstellt" if dry_run else "erstellt"
+        self.stdout.write(
+            self.style.SUCCESS(
+                f"\n{created} LandVerpachtung-Einträge {action}, {skipped} übersprungen."
+            )
+        )

app/stiftung/views/system.py

@@ -1847,6 +1847,124 @@ def app_settings(request):
     return render(request, "stiftung/app_settings.html", context)
 
 
+@login_required
+def email_settings(request):
+    """E-Mail / IMAP configuration with connection test"""
+    import imaplib
+
+    from stiftung.models import AppConfiguration
+    from stiftung.utils.config import get_config
+
+    # Ensure IMAP settings exist in DB (auto-init)
+    imap_defaults = [
+        ("imap_host", "IMAP Server", "Hostname oder IP-Adresse des IMAP-Servers", "", "text", 1),
+        ("imap_port", "IMAP Port", "Port des IMAP-Servers (993 für SSL, 143 für unverschlüsselt)", "993", "number", 2),
+        ("imap_user", "IMAP Benutzername", "Benutzername / E-Mail-Adresse für die IMAP-Anmeldung", "", "text", 3),
+        ("imap_password", "IMAP Passwort", "Passwort für die IMAP-Anmeldung", "", "password", 4),
+        ("imap_folder", "IMAP Ordner", "Postfach-Ordner (Standard: INBOX)", "INBOX", "text", 5),
+        ("imap_use_ssl", "SSL/TLS verwenden", "Sichere Verbindung zum IMAP-Server (empfohlen)", "True", "boolean", 6),
+    ]
+    for key, name, desc, default, stype, order in imap_defaults:
+        AppConfiguration.objects.get_or_create(
+            key=key,
+            defaults={
+                "display_name": name,
+                "description": desc,
+                "value": default,
+                "default_value": default,
+                "setting_type": stype,
+                "category": "email",
+                "order": order,
+            },
+        )
+
+    imap_settings = AppConfiguration.objects.filter(category="email", is_active=True).order_by("order")
+
+    test_result = None
+
+    if request.method == "POST":
+        action = request.POST.get("action", "save")
+
+        if action == "save":
+            updated = 0
+            for setting in imap_settings:
+                field_name = f"setting_{setting.key}"
+                if setting.setting_type == "boolean":
+                    new_val = "True" if field_name in request.POST else "False"
+                else:
+                    new_val = request.POST.get(field_name, setting.value)
+                # Don't overwrite password with empty placeholder
+                if setting.setting_type == "password" and new_val == "":
+                    continue
+                if setting.value != new_val:
+                    setting.value = new_val
+                    setting.save()
+                    updated += 1
+            if updated:
+                messages.success(request, f"{updated} Einstellung(en) gespeichert.")
+            else:
+                messages.info(request, "Keine Änderungen vorgenommen.")
+            return redirect("stiftung:email_settings")
+
+        elif action == "test":
+            # Test IMAP connection with current DB values
+            host = get_config("imap_host")
+            port = int(get_config("imap_port", 993))
+            user = get_config("imap_user")
+            password = get_config("imap_password")
+            use_ssl = get_config("imap_use_ssl", True)
+            folder = get_config("imap_folder", "INBOX")
+
+            if not all([host, user, password]):
+                test_result = {
+                    "success": False,
+                    "message": "IMAP-Server, Benutzername und Passwort müssen konfiguriert sein.",
+                }
+            else:
+                try:
+                    if use_ssl:
+                        conn = imaplib.IMAP4_SSL(host, port)
+                    else:
+                        conn = imaplib.IMAP4(host, port)
+                    conn.login(user, password)
+                    status, _ = conn.select(folder, readonly=True)
+                    if status == "OK":
+                        _, msg_ids = conn.search(None, "ALL")
+                        count = len(msg_ids[0].split()) if msg_ids[0] else 0
+                        _, unseen_ids = conn.search(None, "UNSEEN")
+                        unseen = len(unseen_ids[0].split()) if unseen_ids[0] else 0
+                        test_result = {
+                            "success": True,
+                            "message": f'Verbindung erfolgreich! Ordner "{folder}": {count} E-Mails, davon {unseen} ungelesen.',
+                        }
+                    else:
+                        test_result = {
+                            "success": False,
+                            "message": f'Ordner "{folder}" konnte nicht geöffnet werden.',
+                        }
+                    conn.logout()
+                except imaplib.IMAP4.error as e:
+                    test_result = {
+                        "success": False,
+                        "message": f"IMAP-Fehler: {e}",
+                    }
+                except Exception as e:
+                    test_result = {
+                        "success": False,
+                        "message": f"Verbindungsfehler: {e}",
+                    }
+
+    # Refresh after save
+    imap_settings = AppConfiguration.objects.filter(category="email", is_active=True).order_by("order")
+
+    context = {
+        "imap_settings": imap_settings,
+        "test_result": test_result,
+        "title": "E-Mail / IMAP Konfiguration",
+    }
+    return render(request, "stiftung/email_settings.html", context)
+
+
 # Unterstützungen Views (Destinataer-focused)
 @login_required
 def edit_help_box(request):