feat(auth): remove center api key from frontend login flow

src/pages/LoginPage.tsx

@@ -7,7 +7,6 @@ export default function LoginPage() {
   const navigate = useNavigate()
   const { login, isAuthed, session } = useAuth()
   const [centerApiBase, setCenterApiBase] = useState('http://localhost:7001/api')
-  const [centerApiKey, setCenterApiKey] = useState('')
   const [email, setEmail] = useState('')
   const [password, setPassword] = useState('')
   const [error, setError] = useState('')
@@ -16,7 +15,7 @@ export default function LoginPage() {
     e.preventDefault()
     setError('')
     try {
-      await login(centerApiBase.trim(), centerApiKey.trim(), email, password)
+      await login(centerApiBase.trim(), email, password)
       navigate('/workspace')
     } catch {
       setError('Login failed. Please check your email and password.')
@@ -34,12 +33,6 @@ export default function LoginPage() {
           onChange={(e) => setCenterApiBase(e.target.value)}
           placeholder="Center API Base (e.g. http://localhost:7001/api)"
         />
-        <input
-          className="input"
-          value={centerApiKey}
-          onChange={(e) => setCenterApiKey(e.target.value)}
-          placeholder="Center API Key"
-        />
         <input className="input" value={email} onChange={(e) => setEmail(e.target.value)} placeholder="Email" type="email" />
         <input
           className="input"