Add PostgreSQL, user/squad management, remove private domains from docs

docker-compose.yml

@@ -1,4 +1,20 @@
 services:
+  db:
+    image: postgres:16-alpine
+    container_name: tgvpn-db
+    restart: unless-stopped
+    environment:
+      POSTGRES_USER: tgvpn
+      POSTGRES_PASSWORD: tgvpn
+      POSTGRES_DB: tgvpn
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U tgvpn -d tgvpn"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
   bot:
     build:
       context: .
@@ -6,9 +22,14 @@ services:
     image: tgvpn-bot:latest
     container_name: tgvpn-bot
     restart: unless-stopped
+    depends_on:
+      db:
+        condition: service_healthy
     env_file:
       - .env
     environment:
       BOT_DEBUG: ${BOT_DEBUG:-false}
-    # Long polling — исходящие HTTPS к api.telegram.org
-    # ports не нужны, пока нет webhook
+      DATABASE_URL: postgres://tgvpn:tgvpn@db:5432/tgvpn?sslmode=disable
+
+volumes:
+  pgdata: