feat(ops): v4.0.2 活动图模板、合伙人选择持久化与用户管理主图

HQ 上传底图与码栏；合伙人单选写入 partner_account.activity_poster_id，用户管理下次登录仍显示同一张图。

Co-authored-by: Cursor <cursoragent@cursor.com>

server/dukang-api/src/modules/store/partner-assoc.service.ts

@@ -136,15 +136,51 @@ export class PartnerAssocService {
     const userCount = await this.prisma.user.count({
       where: { assocPartnerAccountId: primary.id },
     });
+    const selectedPoster = primary.activityPosterId
+      ? await this.prisma.activityPoster.findUnique({
+          where: { id: primary.activityPosterId },
+          select: { id: true, status: true },
+        })
+      : null;
+    const activityPosterId =
+      selectedPoster?.status === 'ACTIVE' ? selectedPoster.id.toString() : null;
+
     return {
       partnerId: primary.id.toString(),
       qrcodeUrl: ensured.qrcodeUrl,
       userCount,
       companyName: primary.companyName,
       name: primary.name,
+      activityPosterId,
     };
   }
 
+  async getSelectedActivityPosterId(partnerAccountId: bigint): Promise<string | null> {
+    const primary = await this.partnerCityService.resolvePrimaryAccount(partnerAccountId);
+    if (!primary.activityPosterId) return null;
+    const poster = await this.prisma.activityPoster.findUnique({
+      where: { id: primary.activityPosterId },
+      select: { id: true, status: true },
+    });
+    return poster?.status === 'ACTIVE' ? poster.id.toString() : null;
+  }
+
+  async setSelectedActivityPoster(partnerAccountId: bigint, posterId: bigint | null) {
+    const primary = await this.partnerCityService.resolvePrimaryAccount(partnerAccountId);
+    if (posterId) {
+      const poster = await this.prisma.activityPoster.findFirst({
+        where: { id: posterId, status: 'ACTIVE' },
+        select: { id: true },
+      });
+      if (!poster) throw new BadRequestException('活动图不存在或已下架');
+    }
+    await this.prisma.partnerAccount.update({
+      where: { id: primary.id },
+      data: { activityPosterId: posterId },
+    });
+    return { posterId: posterId?.toString() ?? null };
+  }
+
   async getStats(partnerAccountId: bigint) {
     const primary = await this.partnerCityService.resolvePrimaryAccount(partnerAccountId);
     const { todayStart, monthStart } = dayBounds();