feat: E-Mail-Adresse bestehender Benutzer aenderbar (mit Eindeutigkeits-Pruefung + Audit-Log)

db.py

@@ -137,6 +137,15 @@ def email_exists(email):
             return cur.fetchone() is not None
 
 
+def email_exists_excluding(email, exclude_user_id):
+    """Wie email_exists, aber ignoriert den eigenen Datensatz -- fuer die
+    Eindeutigkeitspruefung beim Aendern der E-Mail eines bestehenden Nutzers."""
+    with get_conn() as conn:
+        with conn.cursor() as cur:
+            cur.execute("SELECT 1 FROM users WHERE email=%s AND id<>%s", (email, exclude_user_id))
+            return cur.fetchone() is not None
+
+
 _USER_COLUMNS = ("id, email, role, active, auth_source, created_at, last_login_at, "
                  "vorname, nachname, telefon, abteilung, adresse")
 
@@ -167,6 +176,12 @@ def update_user_profile(tenant_id, user_id, vorname, nachname, telefon, abteilun
             )
 
 
+def update_user_email(tenant_id, user_id, email):
+    with get_conn() as conn:
+        with conn.cursor() as cur:
+            cur.execute("UPDATE users SET email=%s WHERE tenant_id=%s AND id=%s", (email, tenant_id, user_id))
+
+
 def set_user_role(tenant_id, user_id, role):
     with get_conn() as conn:
         with conn.cursor() as cur: