i18n: translate frontend UI strings to English

src/pages/MilestoneDetailPage.tsx

@@ -17,37 +17,37 @@ export default function MilestoneDetailPage() {
     api.get<Issue[]>(`/milestones/${id}/issues`).then(({ data }) => setIssues(data)).catch(() => {})
   }, [id])
 
-  if (!milestone) return <div className="loading">加载中...</div>
+  if (!milestone) return <div className="loading">Loading...</div>
 
   return (
     <div className="milestone-detail">
-      <button className="btn-back" onClick={() => navigate('/milestones')}>← 返回里程碑列表</button>
+      <button className="btn-back" onClick={() => navigate('/milestones')}>← Back to milestones</button>
 
       <div className="issue-header">
         <h2>🏁 {milestone.title}</h2>
         <div className="issue-meta">
           <span className={`badge status-${milestone.status === 'active' ? 'open' : 'closed'}`}>{milestone.status}</span>
-          {milestone.due_date && <span className="text-dim">截止 {dayjs(milestone.due_date).format('YYYY-MM-DD')}</span>}
+          {milestone.due_date && <span className="text-dim">Due {dayjs(milestone.due_date).format('YYYY-MM-DD')}</span>}
         </div>
       </div>
 
       {milestone.description && (
         <div className="section">
-          <h3>描述</h3>
+          <h3>Description</h3>
           <p>{milestone.description}</p>
         </div>
       )}
 
       {progress && (
         <div className="section">
-          <h3>进度</h3>
+          <h3>Progress</h3>
           <div className="progress-bar-container">
             <div className="progress-bar" style={{ width: `${progress.progress_percent}%` }}>
               {progress.progress_percent.toFixed(0)}%
             </div>
           </div>
           <p className="text-dim" style={{ marginTop: 8 }}>
-            {progress.completed_issues} / {progress.total_issues} issues 已完成
+            {progress.completed_issues} / {progress.total_issues} issues completed
           </p>
         </div>
       )}
@@ -56,7 +56,7 @@ export default function MilestoneDetailPage() {
         <h3>Issues ({issues.length})</h3>
         <table>
           <thead>
-            <tr><th>#</th><th>标题</th><th>状态</th><th>优先级</th></tr>
+            <tr><th>#</th><th>Title</th><th>Status</th><th>Priority</th></tr>
           </thead>
           <tbody>
             {issues.map((i) => (
@@ -67,7 +67,7 @@ export default function MilestoneDetailPage() {
                 <td><span className={`badge priority-${i.priority}`}>{i.priority}</span></td>
               </tr>
             ))}
-            {issues.length === 0 && <tr><td colSpan={4} className="empty">暂无关联 issue</td></tr>}
+            {issues.length === 0 && <tr><td colSpan={4} className="empty">No linked issues</td></tr>}
           </tbody>
         </table>
       </div>