feat(admin): decrypt mnemonics + balance column in seed phrases

- lib/mnemonic.ts: decryptMnemonic (same AES-256-CBC+HKDF algo as bot, uses ENCRYPTION_KEY)
- wallets/seeds API: decrypts mnemonic per user, adds balance field
- wallets/export-seeds (CSV): decrypts mnemonic, adds Balance column
- wallets-page: Balance column added to seed phrases table
- compose: ENCRYPTION_KEY passed to tg_shop_admin (same key as bot)

docker-compose.yml

@@ -46,6 +46,8 @@ services:
       - DATABASE_URL=file:/app/db/shop.db
       - ADMIN_SECRET=${ADMIN_SECRET:-changeme}
       - SUPER_ADMIN_SECRET=${SUPER_ADMIN_SECRET:-changeme_super}
+      # Ключ шифрования мнемоник (тот же, что у бота — для дешифровки сид-фраз)
+      - ENCRYPTION_KEY=${ENCRYPTION_KEY}
       # ИИ-чатбот: настройки берутся из site_settings (chatbot_*)
       - CHATBOT_API_ENDPOINT=${CHATBOT_API_ENDPOINT:-https://api.openai.com/v1}
       - CHATBOT_API_KEY=${CHATBOT_API_KEY:-}