fix: X 일정 상세 UI 개선

- 닉네임과 @id 사이 간격 축소 (PC/모바일)
- 모바일 툴바에서 뒤로가기 버튼 제거, 타이틀 가운데 정렬

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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

@@ -232,7 +232,7 @@ function MobileXSection({ schedule }) {
                   <path d="M22.25 12c0-1.43-.88-2.67-2.19-3.34.46-1.39.2-2.9-.81-3.91s-2.52-1.27-3.91-.81c-.66-1.31-1.91-2.19-3.34-2.19s-2.67.88-3.34 2.19c-1.39-.46-2.9-.2-3.91.81s-1.27 2.52-.81 3.91C2.63 9.33 1.75 10.57 1.75 12s.88 2.67 2.19 3.34c-.46 1.39-.2 2.9.81 3.91s2.52 1.27 3.91.81c.66 1.31 1.91 2.19 3.34 2.19s2.67-.88 3.34-2.19c1.39.46 2.9.2 3.91-.81s1.27-2.52.81-3.91c1.31-.67 2.19-1.91 2.19-3.34zm-11.07 4.57l-3.84-3.84 1.27-1.27 2.57 2.57 5.39-5.39 1.27 1.27-6.66 6.66z" />
                 </svg>
               </div>
-              <span className="text-xs text-gray-500">@{username}</span>
+              <span className="text-xs text-gray-500 -mt-0.5 block">@{username}</span>
             </div>
           </div>
         </div>
@@ -520,16 +520,10 @@ function MobileScheduleDetail() {
     <div className="mobile-layout-container bg-gray-50">
       {/* 헤더 */}
       <div className="flex-shrink-0 bg-white border-b border-gray-100">
-        <div className="flex items-center h-14 px-4">
+        <div className="flex items-center justify-center h-14 px-4">
-          <button onClick={() => window.history.back()} className="p-2 -ml-2 rounded-lg active:bg-gray-100">
+          <span className="text-sm font-medium" style={{ color: schedule.category?.color }}>
-            <ChevronLeft size={24} />
+            {schedule.category?.name}
-          </button>
+          </span>
-          <div className="flex-1 text-center">
-            <span className="text-sm font-medium" style={{ color: schedule.category?.color }}>
-              {schedule.category?.name}
-            </span>
-          </div>
-          <div className="w-10" />
         </div>
       </div>
 

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

@@ -80,7 +80,7 @@ function XSection({ schedule }) {
                   <path d="M22.25 12c0-1.43-.88-2.67-2.19-3.34.46-1.39.2-2.9-.81-3.91s-2.52-1.27-3.91-.81c-.66-1.31-1.91-2.19-3.34-2.19s-2.67.88-3.34 2.19c-1.39-.46-2.9-.2-3.91.81s-1.27 2.52-.81 3.91C2.63 9.33 1.75 10.57 1.75 12s.88 2.67 2.19 3.34c-.46 1.39-.2 2.9.81 3.91s2.52 1.27 3.91.81c.66 1.31 1.91 2.19 3.34 2.19s2.67-.88 3.34-2.19c1.39.46 2.9.2 3.91-.81s1.27-2.52.81-3.91c1.31-.67 2.19-1.91 2.19-3.34zm-11.07 4.57l-3.84-3.84 1.27-1.27 2.57 2.57 5.39-5.39 1.27 1.27-6.66 6.66z" />
                 </svg>
               </div>
-              <span className="text-sm text-gray-500">@{username}</span>
+              <span className="text-sm text-gray-500 -mt-0.5 block">@{username}</span>
             </div>
           </div>
         </div>