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)

quantdinger_vue/src/locales/lang/en-US.js

@@ -1170,6 +1170,10 @@ const locale = {
   'trading-assistant.stopStrategy': 'Stop Strategy',
   'trading-assistant.editStrategy': 'Edit Strategy',
   'trading-assistant.deleteStrategy': 'Delete Strategy',
+  'trading-assistant.startAll': 'Start All',
+  'trading-assistant.stopAll': 'Stop All',
+  'trading-assistant.deleteAll': 'Delete All',
+  'trading-assistant.symbolCount': 'symbols',
   'trading-assistant.status.running': 'Running',
   'trading-assistant.status.stopped': 'Stopped',
   'trading-assistant.status.error': 'Error',
@@ -1202,7 +1206,9 @@ const locale = {
   'trading-assistant.form.testConnection': 'Test Connection',
   'trading-assistant.form.strategyName': 'Strategy Name',
   'trading-assistant.form.symbol': 'Trading Pair',
+  'trading-assistant.form.symbols': 'Trading Pairs (Multi-select)',
   'trading-assistant.form.symbolHint': 'Symbol format depends on the selected market',
+  'trading-assistant.form.symbolsHint': 'Select multiple pairs to create strategies for each',
   'trading-assistant.form.symbolHintCrypto': 'Crypto: use trading pairs like BTC/USDT',
   'trading-assistant.form.symbolHintGeneral': 'Enter the symbol for the selected market (e.g. 600519, AAPL, EURUSD).',
   'trading-assistant.form.initialCapital': 'Initial Capital',
@@ -1312,6 +1318,14 @@ const locale = {
   'trading-assistant.messages.loadIndicatorsFailed': 'Failed to load indicator list, please try again later',
   'trading-assistant.messages.spotLimitations': 'Spot trading has been automatically set to long only with 1x leverage',
   'trading-assistant.messages.autoFillApiConfig': 'Auto-filled API configuration for this exchange from history',
+  'trading-assistant.messages.batchCreateSuccess': 'Successfully created {count} strategies',
+  'trading-assistant.messages.batchStartSuccess': 'Successfully started {count} strategies',
+  'trading-assistant.messages.batchStartFailed': 'Failed to start strategies',
+  'trading-assistant.messages.batchStopSuccess': 'Successfully stopped {count} strategies',
+  'trading-assistant.messages.batchStopFailed': 'Failed to stop strategies',
+  'trading-assistant.messages.batchDeleteSuccess': 'Successfully deleted {count} strategies',
+  'trading-assistant.messages.batchDeleteFailed': 'Failed to delete strategies',
+  'trading-assistant.messages.batchDeleteConfirm': 'Are you sure you want to delete {count} strategies in group "{name}"? This action cannot be undone.',
   'trading-assistant.placeholders.selectIndicator': 'Please select an indicator',
   'trading-assistant.placeholders.selectExchange': 'Please select an exchange',
   'trading-assistant.placeholders.selectMarketCategory': 'Please select market category',
@@ -1320,6 +1334,7 @@ const locale = {
   'trading-assistant.placeholders.inputPassphrase': 'Please enter Passphrase',
   'trading-assistant.placeholders.inputStrategyName': 'Please enter strategy name',
   'trading-assistant.placeholders.selectSymbol': 'Please select trading pair',
+  'trading-assistant.placeholders.selectSymbols': 'Please select trading pairs (multi-select)',
   'trading-assistant.placeholders.inputSymbol': 'Please enter symbol',
   'trading-assistant.placeholders.selectTimeframe': 'Please select timeframe',
   'trading-assistant.placeholders.selectKlinePeriod': 'Please select K-line period',
@@ -1341,6 +1356,7 @@ const locale = {
   'trading-assistant.validation.testConnectionFailed': 'Connection test failed, please check the configuration and test again',
   'trading-assistant.validation.strategyNameRequired': 'Please enter strategy name',
   'trading-assistant.validation.symbolRequired': 'Please select trading pair',
+  'trading-assistant.validation.symbolsRequired': 'Please select at least one trading pair',
   'trading-assistant.validation.initialCapitalRequired': 'Please enter initial capital',
   'trading-assistant.validation.leverageRequired': 'Please enter leverage',
   'trading-assistant.validation.emailInvalid': 'Invalid email address',