fix(users): use creators_map instead of relationship for created_by display

Self-referential FK with lazy='joined' causes DetachedInstanceError after
db.close(). Build a simple dict lookup in the route instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

blueprints/admin/routes.py

@@ -168,6 +168,13 @@ def admin_users():
 
         locked_count = sum(1 for u in users if u.locked_until and u.locked_until > datetime.utcnow())
 
+        # Build created_by map: user_id → creator name (for "added by" display)
+        creator_ids = {u.created_by_id for u in users if u.created_by_id}
+        creators_map = {}
+        if creator_ids:
+            creators = db.query(User.id, User.name, User.email).filter(User.id.in_(creator_ids)).all()
+            creators_map = {c.id: c.name or c.email for c in creators}
+
         return render_template(
             'admin/users.html',
             users=users,
@@ -178,6 +185,7 @@ def admin_users():
             unverified_count=unverified_count,
             pending_company_count=pending_company_count,
             locked_count=locked_count,
+            creators_map=creators_map,
             now=datetime.utcnow()
         )
     finally:

templates/admin/users.html

@@ -1245,8 +1245,8 @@
                 <td style="font-size: var(--font-size-sm); color: var(--text-secondary);"
                     data-sort-value="{{ user.created_at.strftime('%Y%m%d%H%M') }}">
                     {{ user.created_at.strftime('%d.%m.%Y %H:%M') }}
-                    {% if user.created_by_id %}
+                    {% if user.created_by_id and creators_map.get(user.created_by_id) %}
-                        <br><span style="font-size: 0.75rem; color: var(--text-muted, #9CA3AF);" title="Dodany przez {{ user.created_by.name or user.created_by.email }}">dodał: {{ user.created_by.name or user.created_by.email }}</span>
+                        <br><span style="font-size: 0.75rem; color: var(--text-muted, #9CA3AF);" title="Dodany przez {{ creators_map[user.created_by_id] }}">dodał: {{ creators_map[user.created_by_id] }}</span>
                     {% else %}
                         <br><span style="font-size: 0.75rem; color: var(--text-muted, #9CA3AF);">samorejestracja</span>
                     {% endif %}