feat: 代码片段功能与 Markdown 内嵌片段渲染、文档截图等

frontend/app/register/RegisterClient.tsx

@@ -190,7 +190,7 @@ export default function RegisterClient({
               />
               <button
                 type="button"
-                className="btn btn-line shrink-0"
+                className="btn btn-code shrink-0"
                 disabled={sending || countdown > 0 || !email}
                 onClick={async () => {
                   // 点击即锁定，防止重复发送
@@ -201,7 +201,7 @@ export default function RegisterClient({
                       email,
                       purpose: "register",
                     });
-                    setSentMessage(r.message);
+                    setSentMessage("验证码已发送，请查收邮箱");
                     startCountdown();
                   } catch (err) {
                     setError((err as Error).message);
@@ -211,7 +211,7 @@ export default function RegisterClient({
                 }}
               >
                 {sending
-                  ? "正在排队…"
+                  ? "发送中…"
                   : countdown > 0
                     ? `${countdown}s 后可重发`
                     : "发送验证码"}