feat(auth): allowlist private для LAN return_to

Co-authored-by: Cursor <[email protected]>

.env.example

@@ -13,7 +13,7 @@ ADMIN_PASSWORD=admin
 ADMIN_NAME=Admin
 
 # Allowed return_to hosts (comma-separated), e.g. .shnt.top or full origins
-RETURN_TO_ALLOWLIST=.shnt.top,localhost,http://localhost:5173,http://localhost:5174
+RETURN_TO_ALLOWLIST=.shnt.top,localhost,private,http://localhost:5173,http://localhost:5174
 
 # ReUI PRO (apps/web/components.json → @reui Authorization)
 # Ключ: https://reui.io/docs/license-setup — класть в apps/web/.env.local (gitignored)