feat(frontend): implement center auth session flow with route guard

src/pages/LoginPage.tsx

@@ -1,8 +1,41 @@
+import { useState } from 'react'
+import type { FormEvent } from 'react'
+import { useNavigate } from 'react-router-dom'
+import { useAuth } from '../auth/auth-context'
+
 export default function LoginPage() {
+  const navigate = useNavigate()
+  const { login, isAuthed, session } = useAuth()
+  const [email, setEmail] = useState('')
+  const [password, setPassword] = useState('')
+  const [error, setError] = useState('')
+
+  async function onSubmit(e: FormEvent) {
+    e.preventDefault()
+    setError('')
+    try {
+      await login(email, password)
+      navigate('/workspace')
+    } catch {
+      setError('登录失败，请检查账号密码')
+    }
+  }
+
   return (
     <section>
       <h2>登录</h2>
-      <p>下一步接入 Center 登录与 token 管理。</p>
+      {isAuthed ? <p>当前用户：{session?.user.email}</p> : null}
+      <form onSubmit={onSubmit} style={{ display: 'grid', gap: 8, maxWidth: 420 }}>
+        <input value={email} onChange={(e) => setEmail(e.target.value)} placeholder="Email" type="email" />
+        <input
+          value={password}
+          onChange={(e) => setPassword(e.target.value)}
+          placeholder="Password"
+          type="password"
+        />
+        <button type="submit">登录</button>
+      </form>
+      <p>{error}</p>
     </section>
   )
 }

src/pages/WorkspacePage.tsx

@@ -33,6 +33,11 @@ export default function WorkspacePage() {
     <section>
       <h2>工作台</h2>
       <form onSubmit={onSave} style={{ display: 'grid', gap: 8, maxWidth: 760 }}>
+        <input
+          value={form.centerApiBase}
+          onChange={(e) => setForm((v) => ({ ...v, centerApiBase: e.target.value }))}
+          placeholder="Center API Base"
+        />
         <input
           value={form.guildApiBase}
           onChange={(e) => setForm((v) => ({ ...v, guildApiBase: e.target.value }))}