feat: initial frontend - React + TypeScript + Vite

- Login page with JWT auth
- Dashboard with stats and charts
- Issues list with pagination, filtering
- Issue detail with comments, status transitions
- Create issue form
- Dark theme UI
- Docker (nginx) with API proxy to backend
- Sidebar navigation

src/pages/DashboardPage.tsx

@@ -0,0 +1,75 @@
+import { useState, useEffect } from 'react'
+import api from '@/services/api'
+import type { DashboardStats } from '@/types'
+
+export default function DashboardPage() {
+  const [stats, setStats] = useState<DashboardStats | null>(null)
+
+  useEffect(() => {
+    api.get<DashboardStats>('/dashboard/stats').then(({ data }) => setStats(data))
+  }, [])
+
+  if (!stats) return <div className="loading">加载中...</div>
+
+  const statusColors: Record<string, string> = {
+    open: '#3b82f6', in_progress: '#f59e0b', resolved: '#10b981',
+    closed: '#6b7280', blocked: '#ef4444',
+  }
+  const priorityColors: Record<string, string> = {
+    low: '#6b7280', medium: '#3b82f6', high: '#f59e0b', critical: '#ef4444',
+  }
+
+  return (
+    <div className="dashboard">
+      <h2>📊 仪表盘</h2>
+
+      <div className="stats-grid">
+        <div className="stat-card total">
+          <span className="stat-number">{stats.total_issues}</span>
+          <span className="stat-label">总 Issues</span>
+        </div>
+        {Object.entries(stats.by_status).map(([k, v]) => (
+          <div className="stat-card" key={k} style={{ borderLeftColor: statusColors[k] || '#ccc' }}>
+            <span className="stat-number">{v}</span>
+            <span className="stat-label">{k}</span>
+          </div>
+        ))}
+      </div>
+
+      <div className="section">
+        <h3>按优先级</h3>
+        <div className="bar-chart">
+          {Object.entries(stats.by_priority).map(([k, v]) => (
+            <div className="bar-row" key={k}>
+              <span className="bar-label">{k}</span>
+              <div className="bar" style={{
+                width: `${Math.max((v / stats.total_issues) * 100, 5)}%`,
+                backgroundColor: priorityColors[k] || '#ccc',
+              }}>{v}</div>
+            </div>
+          ))}
+        </div>
+      </div>
+
+      <div className="section">
+        <h3>最近 Issues</h3>
+        <table>
+          <thead>
+            <tr><th>ID</th><th>标题</th><th>状态</th><th>优先级</th><th>类型</th></tr>
+          </thead>
+          <tbody>
+            {stats.recent_issues.map((i) => (
+              <tr key={i.id}>
+                <td>#{i.id}</td>
+                <td><a href={`/issues/${i.id}`}>{i.title}</a></td>
+                <td><span className={`badge status-${i.status}`}>{i.status}</span></td>
+                <td><span className={`badge priority-${i.priority}`}>{i.priority}</span></td>
+                <td>{i.issue_type}</td>
+              </tr>
+            ))}
+          </tbody>
+        </table>
+      </div>
+    </div>
+  )
+}