feat(core): notification inbox infinite scroll + command palette fix (+ pending WIP)

消息中心:全量渲染 → 真·后端分页滚动加载
- backend(ops/views): NotificationPagination(10/页,page_size 可覆盖)+
  响应回 type_counts(按收件人绝对计数,不受分页/搜索影响)
- frontend(messages): 自管分页,滚到底加载下一批;tab/搜索走服务端并重置到第1页;
  代号作废在途旧请求防切换卡空白;乐观标已读;「已加载 X / Y」分母用当前筛选总数
- api/App/types: listNotifications 支持 page/page_size/search;allNotifications 携带 type_counts

命令面板(侧边栏搜索):修复点开后 UI 错位
- app-shell: 遮罩 className 漏了基类 shell-command-bg(只有 .show)致无定位塌到左下;
  补回基类 + header 类名对齐 .shell-command-h
- messages-page.css: 工作台收进视口高度,收件箱在面板内滚动

本次提交一并带入此前若干未提交 WIP(account/ai-tools/library/pipeline/products/settings +
accounts/ai/assets/billing/projects 后端),按用户要求整体推 dev。

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

core/backend/apps/billing/views.py

@@ -56,7 +56,27 @@ def ledgers(request):
         queryset = queryset.filter(project_id=project_id)
     if user_id:
         queryset = queryset.filter(user_id=user_id)
-    return Response(CreditLedgerSerializer(queryset[:100], many=True).data)
+    # 服务端分页:总数随流水增长(原先写死 [:100] 导致永远 100 条)
+    try:
+        page = max(1, int(request.query_params.get("page", 1)))
+    except (TypeError, ValueError):
+        page = 1
+    try:
+        page_size = int(request.query_params.get("page_size", 10))
+    except (TypeError, ValueError):
+        page_size = 10
+    page_size = max(1, min(page_size, 100))
+    total = queryset.count()
+    start = (page - 1) * page_size
+    rows = queryset[start:start + page_size]
+    return Response(
+        {
+            "count": total,
+            "page": page,
+            "page_size": page_size,
+            "results": CreditLedgerSerializer(rows, many=True).data,
+        }
+    )
 
 
 @api_view(["POST"])