feat(admin): serverseitige Pydantic-Validatoren für Notfall-Profilfelder

Härtung zusätzlich zur Frontend-Prüfung: AdminUserPrefsUpdate validiert
nicht-leere Werte (leer/None = konform) und liefert sonst 422:
- postal_code: 5 Ziffern · phone_mobile/phone_landline: Telefonformat
- birth_date: TT.MM.JJJJ (echtes Datum) · emergency_contacts: CSV gültiger
  E-Mails · emergency_phones: CSV gültiger Nummern
Regeln spiegeln die Frontend-Validierung. 10 neue Tests (gültig/leer/ungültig),
Suite 250 grün.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_admin_prefs_validation.py

@@ -0,0 +1,36 @@
+import pytest
+from pydantic import ValidationError
+
+from app.schemas import AdminUserPrefsUpdate
+
+
+def test_valid_profile_passes():
+    AdminUserPrefsUpdate(
+        full_name="Frieda Schlüter", postal_code="50670",
+        phone_mobile="+4915127747511", phone_landline="040 123456",
+        birth_date="14.02.1976",
+        emergency_contacts="a@b.de, c@d.com",
+        emergency_phones="+4915127747511, 040 12345",
+        location_consent=True,
+    )
+
+
+def test_empty_and_none_pass():
+    # Leere/None-Felder gelten als konform (optional).
+    AdminUserPrefsUpdate(postal_code="", phone_mobile="", birth_date="",
+                         emergency_contacts="", emergency_phones=None)
+
+
+@pytest.mark.parametrize("field,value", [
+    ("postal_code", "123"),
+    ("postal_code", "abcde"),
+    ("phone_mobile", "hallo"),
+    ("phone_landline", "xx"),
+    ("birth_date", "1976-02-14"),
+    ("birth_date", "31.02.2020"),
+    ("emergency_contacts", "a@b.de, nope"),
+    ("emergency_phones", "kein-telefon!!"),
+])
+def test_invalid_rejected(field, value):
+    with pytest.raises(ValidationError):
+        AdminUserPrefsUpdate(**{field: value})