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

Author: victoreduardo

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

@@ -0,0 +1,17 @@
+/*
+  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
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM pg_indexes 
+        WHERE indexname = 'Chat_instanceId_remoteJid_key'
+    ) THEN
+        CREATE UNIQUE INDEX "Chat_instanceId_remoteJid_key" ON "Chat"("instanceId", "remoteJid");
+    END IF;
+END
+$$;

prisma/postgresql-schema.prisma

@@ -125,6 +125,7 @@ model Chat {
   Instance       Instance  @relation(fields: [instanceId], references: [id], onDelete: Cascade)
   instanceId     String
   unreadMessages Int       @default(0)
+  @@unique([instanceId, remoteJid])
   @@index([instanceId])
   @@index([remoteJid])
 }