feat(server): 站内通知基础设施与关键事件触发(F14,F30)

- 新增 notifications 表与 API(list/mark-read)
- submit/approve/reject/return/transfer/pay/forgot-password 写入站内通知
- 通知失败降级，不阻塞主流程

server/src/services/notifications/index.js

@@ -0,0 +1,56 @@
+function uniq(values) {
+  return Array.from(new Set((values ?? []).filter(Boolean)));
+}
+
+async function resolveRecipientsForAssignee(tx, params) {
+  if (params.assigneeId) {
+    return [params.assigneeId];
+  }
+
+  if (params.assigneeRole) {
+    const rows = await tx.employeeRole.findMany({
+      where: {
+        role_code: params.assigneeRole,
+        employee: {
+          status: "active",
+        },
+      },
+      select: {
+        employee_id: true,
+      },
+    });
+
+    return rows.map((row) => row.employee_id);
+  }
+
+  return [];
+}
+
+async function createNotifications(tx, input) {
+  const recipientIds = uniq(input.recipientEmployeeIds);
+  if (recipientIds.length === 0) {
+    return { count: 0 };
+  }
+
+  const title = String(input.title ?? "").slice(0, 200);
+  const body = input.body != null ? String(input.body).slice(0, 5000) : null;
+  const type = String(input.type ?? "").slice(0, 64);
+  const targetType = input.targetType != null ? String(input.targetType).slice(0, 64) : null;
+
+  return tx.notification.createMany({
+    data: recipientIds.map((recipientId) => ({
+      recipient_employee_id: recipientId,
+      type,
+      title,
+      body,
+      target_type: targetType,
+      target_id: input.targetId ?? null,
+    })),
+  });
+}
+
+module.exports = {
+  createNotifications,
+  resolveRecipientsForAssignee,
+};
+