feat: add unique index on chat to allow update chat label

prisma/postgresql-migrations/20250314220553_add_unique_chat/migration.sql

@@ -0,0 +1,8 @@
+/*
+  Warnings:
+
+  - A unique constraint covering the columns `[instanceId,remoteJid]` on the table `Chat` will be added. If there are existing duplicate values, this will fail.
+
+*/
+-- CreateIndex
+CREATE UNIQUE INDEX "Chat_instanceId_remoteJid_key" ON "Chat"("instanceId", "remoteJid");

prisma/postgresql-schema.prisma

@@ -127,6 +127,7 @@ model Chat {
   instanceId     String
   unreadMessages Int       @default(0)
 
+  @@unique([instanceId, remoteJid])
   @@index([instanceId])
   @@index([remoteJid])
 }