feat(I18n) 添加I18n相关功能，支持中文和英文

src/client/components/IpInput.tsx

@@ -1,5 +1,6 @@
 import { useState, useEffect } from 'react'
 import { fetchUserIp } from '../api/latency'
+import { useLanguage } from '../contexts/LanguageContext'
 import './IpInput.css'
 
 interface IpInputProps {
@@ -19,19 +20,20 @@ export default function IpInput({ onTest, testing }: IpInputProps) {
   const [target, setTarget] = useState('')
   const [loading, setLoading] = useState(true)
   const [error, setError] = useState('')
+  const { t } = useLanguage()
 
   useEffect(() => {
     fetchUserIp()
       .then(setTarget)
-      .catch(() => setError('Failed to detect IP'))
+      .catch(() => setError(t('IP检测失败', 'Failed to detect IP')))
       .finally(() => setLoading(false))
-  }, [])
+  }, [t])
 
   const handleSubmit = (e: React.FormEvent) => {
     e.preventDefault()
     const trimmed = target.trim()
     if (!isValidTarget(trimmed)) {
-      setError('Invalid IP address or domain')
+      setError(t('无效的IP地址或域名', 'Invalid IP address or domain'))
       return
     }
     setError('')
@@ -48,7 +50,7 @@ export default function IpInput({ onTest, testing }: IpInputProps) {
             setTarget(e.target.value)
             setError('')
           }}
-          placeholder={loading ? 'Detecting IP...' : 'Enter IP or domain (e.g., 8.8.8.8 or google.com)'}
+          placeholder={loading ? t('正在检测IP...', 'Detecting IP...') : t('输入IP或域名（如 8.8.8.8 或 google.com）', 'Enter IP or domain (e.g., 8.8.8.8 or google.com)')}
           className={`ip-input ${error ? 'ip-input-error' : ''}`}
           disabled={testing || loading}
         />
@@ -58,10 +60,10 @@ export default function IpInput({ onTest, testing }: IpInputProps) {
         {testing ? (
           <>
             <span className="spinner" />
-            Testing...
+            {t('测试中...', 'Testing...')}
           </>
         ) : (
-          'Test Latency'
+          t('开始测试', 'Test Latency')
         )}
       </button>
     </form>