feat(edit-plans): 列表页新增 result_count 视频数列

- EditPlan interface 新增 result_count: number 字段
- EditPlans.tsx 表格在时长列后新增「视频数」列
- 居中展示，有值显示数字，无值显示 —

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/web/src/api/editPlans.ts

@@ -130,6 +130,8 @@ export interface EditPlan {
   name: string;
   status: EditPlanStatus;
   total_duration: number;
+  /** 生成视频数量（后端 EditPlanResponse.result_count） */
+  result_count: number;
   config: EditPlanConfig;
   created_at: string;
   updated_at: string;

apps/web/src/pages/edit-plans/EditPlans.tsx

@@ -254,6 +254,16 @@ export default function EditPlans() {
         <span className="plan-duration">{formatDuration(seconds)}</span>
       ),
     },
+    {
+      title: "视频数",
+      dataIndex: "result_count",
+      key: "result_count",
+      width: 80,
+      align: "center",
+      render: (count: number) => (
+        <span className="plan-result-count">{count > 0 ? count : "—"}</span>
+      ),
+    },
     {
       title: "创建时间",
       dataIndex: "created_at",