style: X 게시글 하이퍼링크 색상을 파란색으로 변경 (해시태그와 구분)

- 해시태그: primary (초록)
- URL 링크: blue-500 (파란)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/mobile/schedule/ScheduleDetail.jsx

@@ -39,7 +39,7 @@ function linkifyText(text) {
       // URL
       const href = matched.startsWith('http') ? matched : `https://${matched}`;
       parts.push(
-        <a key={match.index} href={href} target="_blank" rel="noopener noreferrer" className="text-primary hover:underline">
+        <a key={match.index} href={href} target="_blank" rel="noopener noreferrer" className="text-blue-500 hover:underline">
           {matched}
         </a>
       );

frontend/src/pages/pc/public/schedule/sections/XSection.jsx

@@ -33,7 +33,7 @@ function linkifyText(text) {
     } else {
       const href = matched.startsWith('http') ? matched : `https://${matched}`;
       parts.push(
-        <a key={match.index} href={href} target="_blank" rel="noopener noreferrer" className="text-primary hover:underline">
+        <a key={match.index} href={href} target="_blank" rel="noopener noreferrer" className="text-blue-500 hover:underline">
           {matched}
         </a>
       );