实现制度签收轻量回执（05-28-oa-policy-acknowledgement-v1）

server/prisma/schema.prisma

@@ -683,6 +683,8 @@ model Employee {
   email_login_codes                    EmailLoginCode[]
   lifecycle_events                     EmployeeLifecycleEvent[]
   checklist_tasks                      EmployeeChecklistTask[]
+  portal_announcement_acknowledgements PortalAnnouncementAcknowledgement[] @relation("PortalAnnouncementAcknowledgementEmployee")
+  portal_announcement_acknowledgement_actions PortalAnnouncementAcknowledgement[] @relation("PortalAnnouncementAcknowledgementActor")
   presence_records                     EmployeePresence[]
   attendance_records                   AttendanceRecord[]
   weekly_reports                       WeeklyReport[]
@@ -1876,24 +1878,51 @@ model PaymentBatchReceiptAttachment {
 }
 
 model PortalAnnouncement {
-  id        String    @id @default(uuid()) @db.Uuid
-  title     String
-  summary   String
-  link_url  String?
-  starts_at DateTime?
-  ends_at   DateTime?
-  enabled   Boolean   @default(true)
-  priority  Int       @default(100)
+  id                         String    @id @default(uuid()) @db.Uuid
+  title                      String
+  summary                    String
+  link_url                   String?
+  starts_at                  DateTime?
+  ends_at                    DateTime?
+  enabled                    Boolean   @default(true)
+  priority                   Int       @default(100)
+  category                   String    @default("general")
+  requires_acknowledgement   Boolean   @default(false)
+  acknowledgement_statement  String?
+  acknowledgement_due_at     DateTime?
 
   created_at DateTime @default(now())
   created_by String?  @db.Uuid
   updated_at DateTime @default(now()) @updatedAt
   updated_by String?  @db.Uuid
 
+  acknowledgements PortalAnnouncementAcknowledgement[]
+
   @@index([enabled, priority, starts_at, ends_at], map: "idx_portal_announcements_enabled_priority")
   @@map("portal_announcements")
 }
 
+model PortalAnnouncementAcknowledgement {
+  id                 String   @id @default(uuid()) @db.Uuid
+  announcement_id    String   @db.Uuid
+  employee_id        String   @db.Uuid
+  acknowledged_at    DateTime @default(now())
+  statement_snapshot String
+  title_snapshot     String
+  summary_snapshot   String
+  actor_id           String   @db.Uuid
+  created_at         DateTime @default(now())
+
+  announcement PortalAnnouncement @relation(fields: [announcement_id], references: [id], onDelete: Cascade)
+  employee     Employee           @relation("PortalAnnouncementAcknowledgementEmployee", fields: [employee_id], references: [id], onDelete: Restrict)
+  actor        Employee           @relation("PortalAnnouncementAcknowledgementActor", fields: [actor_id], references: [id], onDelete: Restrict)
+
+  @@unique([announcement_id, employee_id])
+  @@index([employee_id, acknowledged_at])
+  @@index([announcement_id, acknowledged_at])
+  @@map("portal_announcement_acknowledgements")
+}
+
 model WorkspaceSetting {
   id                     String                        @id @default(uuid()) @db.Uuid
   profile                WorkspaceProfile              @default(small_team_internal)