refactor(routes): 刪除 dashboard brand_assets 重複路由

ADR-017 Phase 3f-1 dashboard/misc sprint

routes/dashboard_routes.py

@@ -665,10 +665,3 @@ def index():
         return f"系統維護中，錯誤詳情：{e}"
     finally:
         session.close()
-
-
-@dashboard_bp.route('/brand_assets')
-@login_required
-def brand_assets():
-    """顯示品牌資產庫"""
-    return render_template('brand_assets.html')