perf(core): 项目列表改轻量序列化 + 计数走真实 count,根治刷新 2-3s

/api/projects/ 列表此前与详情共用重序列化器(嵌套 阶段/片段/故事板/时间线 + 每资产算 url),
20 个项目把全套关联拉出 → 实测 ~2-3s,正是每次刷新慢的主因。

- 新增 ProjectListSerializer(轻:名/状态/阶段/product/封面/脚本数/镜数);
  ProjectViewSet.get_serializer_class 列表用轻的、详情用全量;
  get_queryset 列表走轻查询(select_related product + annotate 计数,不做那串 12 个重 prefetch)。
  实测 /api/projects/ 2-3s → 0.48s。
- 新增 /api/projects/summary/(total + by_status,只跑 COUNT,不拉项目对象)。
- 计数显示(侧栏徽标 / 仪表盘 总项目·SKU·N 个)改用分页响应的真实 count(productTotal/projectTotal),
  不再用「已加载 20 条」的长度;projects 列表页脚本状态/镜数改读 *_count 字段。

闸:9 页全绿、无瀑布、API 全过;projects 端点提速 ~5x。

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

core/frontend/src/components/app-shell.tsx

@@ -130,16 +130,19 @@ const PAGE_TO_NAV: Partial<Record<Page, Page>> = {
   settingsNotify: "settings"
 };
 
-export function Sidebar({ page, navigate, user, team, products, projects }: {
+export function Sidebar({ page, navigate, user, team, products, projects, productTotal, projectTotal }: {
   page: Page;
   navigate: Navigate;
   user: User;
   team: Team | null;
   products: Product[];
   projects: Project[];
+  productTotal?: number;
+  projectTotal?: number;
 }) {
   const activeNav = PAGE_TO_NAV[page];
-  const badges: Partial<Record<string, number>> = { products: products.length, projects: projects.length };
+  // 徽标用后端真实总数(分页 count),不用已加载的页内条数
+  const badges: Partial<Record<string, number>> = { products: productTotal ?? products.length, projects: projectTotal ?? projects.length };
   const avatar = (team?.name || user.username || "A").slice(0, 1).toUpperCase();
 
   // 收窄/展开导航:与设计稿 Shell.toggleSidebarCollapse 一致 —— 切 body.sidebar-collapsed