fix: Remove duplicate selectExchange key in translations

Fixed TypeScript compilation error TS1117 caused by duplicate
'selectExchange' key in both English and Chinese translation objects.

The key was already defined in the "AI Traders Management" section,
so removed the duplicate from "AI Traders Page - Additional" section.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

web/src/i18n/translations.ts

@@ -226,7 +226,6 @@ export const translations = {
     editExchange: 'Edit Exchange',
     addExchange: 'Add Exchange',
     confirmDeleteExchange: 'Are you sure you want to delete this exchange configuration?',
-    selectExchange: 'Select Exchange',
     pleaseSelectExchange: 'Please select an exchange',
     enterSecretKey: 'Enter secret key',
     enterPassphrase: 'Enter Passphrase (Required for OKX)',
@@ -529,7 +528,6 @@ export const translations = {
     editExchange: '编辑交易所',
     addExchange: '添加交易所',
     confirmDeleteExchange: '确定要删除此交易所配置吗？',
-    selectExchange: '选择交易所',
     pleaseSelectExchange: '请选择交易所',
     enterSecretKey: '输入密钥',
     enterPassphrase: '输入Passphrase (OKX必填)',