feat(i18n): add missing translations for trading-assistant modal
- Add step2Params and step3Signal translations
- Add execution mode related translations (signal/live)
- Add notification channel translations (browser/email/phone/telegram/discord/webhook)
- Add live trading config translations (savedCredential, credentialName, etc.)
- Add batch operation message translations (batchCreateSuccess, batchStart/Stop/Delete)
- Add placeholders for email, phone, telegram, discord, webhook inputs
- Add validation messages for email and notify channel
- Add strategy group translations (startAll, stopAll, deleteAll, symbolCount)
- Support both zh-CN (Simplified Chinese) and zh-TW (Traditional Chinese)
TIANHE
e7cb9c6493