feat(reliability): close messaging gateway P0 gaps

telegram-gateway/src/database/entities/tg-chat.entity.ts

@@ -6,6 +6,7 @@ import {
   UpdateDateColumn,
   ManyToOne,
   JoinColumn,
+  Index,
 } from 'typeorm';
 import { TgAccount } from './tg-account.entity';
 
@@ -18,6 +19,7 @@ export enum ChatType {
 }
 
 @Entity('tg_chats')
+@Index('IDX_tg_chat_account_identity', ['accountId', 'tgChatId'], { unique: true })
 export class TgChat {
   @PrimaryGeneratedColumn('uuid')
   id: string;