Backoffice stage 2: chats (support + concierge, files)

- ChatThread per client/provider and channel; messages get files, internal notes,
  source (bot/mini app) and delivery errors; reply templates. Migration moves old
  concierge messages into threads.
- Routing: subscribers write to the concierge, others to support; /support and
  /concierge in the client bot; staff can take, transfer, close and move threads.
- Telegram: photos/documents from clients and providers, replies with the channel
  header, files sent from storage, notifications only to the assignee or the
  channel's staff, "Reply" into a specific thread.
- New admin: /chats with list, conversation, notes, files, templates, client panel;
  "Message" button on the client card; dashboard counts threads awaiting reply.
- Client mini app: in-app chat screen sharing the same conversation.
- Old admin keeps working on the same data (notes hidden there).
- Tests for routing, notes, assign/close/move, lists, recipients; separate test DB
  via TEST_DB_NAME; dev:chats-demo script.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/miniapp-client/vite.config.ts

@@ -2,12 +2,14 @@ import react from '@vitejs/plugin-react';
 import { defineConfig } from 'vite';
 
 // В разработке API проксируется — Mini App и API на одном origin (удобно и для туннеля https)
+// API_PROXY — другой локальный API (например, второй экземпляр на соседнем порту)
+const api = process.env.API_PROXY ?? 'http://localhost:4000';
 export default defineConfig({
   plugins: [react()],
   server: {
     host: true,
     allowedHosts: true,
-    proxy: { '/trpc': 'http://localhost:4000', '/files': 'http://localhost:4000', '/client-log': 'http://localhost:4000' },
+    proxy: { '/trpc': api, '/files': api, '/client-log': api },
   },
   build: { target: 'es2022', sourcemap: true },
 });