fix: harden real backend workflows and channel connections

api/prisma/schema.prisma

@@ -352,6 +352,7 @@ model SmsApplication {
   sendTasks   SmsSendTask[]
   batchTasks  SmsBatchTask[]
   messageRecords SmsMessageRecord[]
+  connectionStates CmppConnectionState[]
 
   @@index([tenantId, status])
 }
@@ -502,6 +503,7 @@ model SmsChannel {
 model CmppConnectionState {
   id                 String   @id @default(cuid())
   tenantId           String?
+  applicationId      String?
   channelId          String
   connectionId       String
   status             String   @default("disconnected")
@@ -515,11 +517,13 @@ model CmppConnectionState {
   updatedAt          DateTime @updatedAt
   createdAt          DateTime @default(now())
 
-  tenant  Tenant?    @relation(fields: [tenantId], references: [id])
-  channel SmsChannel @relation(fields: [channelId], references: [id])
+  tenant      Tenant?         @relation(fields: [tenantId], references: [id])
+  application SmsApplication? @relation(fields: [applicationId], references: [id])
+  channel     SmsChannel      @relation(fields: [channelId], references: [id])
 
-  @@unique([channelId, connectionId])
+  @@unique([applicationId, channelId, connectionId])
   @@index([tenantId, status])
+  @@index([applicationId, status])
   @@index([channelId, status])
 }