feat(admin): reset a user's recommendations from the users panel

- POST /admin/users/{id}/reset-recommendations clears the taste profile
  (onboarding, CF vector, bandit), play stats and wave impressions; likes,
  dislikes and history stay, wave sessions stay so a playing wave keeps going
- moderators may reset plain users, admins anyone including themselves;
  the reset is written to the audit log
- users panel gets the menu action with a confirmation; docs updated

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/api.md

@@ -114,6 +114,7 @@
 | POST | `/admin/users` `{username, display_name, role}` → `{user, temporary_password}` (пароль генерирует сервер, `must_change_password = true`) | moderator: только `role=user`; admin: любые |
 | PATCH | `/admin/users/{id}` `{display_name?, role?, is_blocked?}` | role — только admin |
 | POST | `/admin/users/{id}/reset-password` → `{temporary_password}` | moderator — только для user |
+| POST | `/admin/users/{id}/reset-recommendations` → 204: рекомендации с нуля (профиль, статистика, показы волны) | moderator — только для user |
 | DELETE | `/admin/users/{id}` | admin |
 | GET/POST | `/admin/sources` | admin |
 | GET/PATCH/DELETE | `/admin/sources/{id}` | admin |