fix:업로드 진행률 버튼 흰색 배경 문제 수정

- disabled 속성 제거 (브라우저 기본 스타일이 Tailwind을 덮어씌움)
- 클릭 가드로 중복 클릭 방지 대체
- !important로 배경/글자색 강제 적용 (indigo-900/white)
- is-loading 클래스로 진행 중 상태 명확히 구분

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

resources/views/video/tutorial/index.blade.php

@@ -61,15 +61,21 @@
     }
     .screenshot-add-btn:hover { border-color: #818cf8; color: #6366f1; background: #f5f3ff; }
     .progress-btn {
-        position: relative; overflow: hidden; min-width: 260px;
+        position: relative; overflow: hidden; min-width: 280px;
+        background: #4338ca !important; color: #fff !important;
+        border: none !important; opacity: 1 !important;
     }
     .progress-btn .progress-fill {
         position: absolute; left: 0; top: 0; bottom: 0;
-        background: rgba(255,255,255,0.15); transition: width 0.3s ease-out;
+        background: rgba(255,255,255,0.2); transition: width 0.3s ease-out;
+        pointer-events: none;
     }
     .progress-btn .btn-content {
         position: relative; z-index: 1; display: flex; align-items: center; justify-content: center; gap: 0.5rem;
     }
+    .progress-btn.is-loading {
+        background: #312e81 !important; cursor: wait !important;
+    }
     .analysis-card {
         background: #fff; border: 1px solid #e5e7eb; border-radius: 0.75rem;
         padding: 1rem; margin-bottom: 0.75rem; box-shadow: 0 1px 2px rgba(0,0,0,.05);
@@ -393,13 +399,8 @@ className={`screenshot-thumb ${dragIdx === i ? 'dragging' : ''} ${dragOverIdx ==
             {files.length > 0 && (
                 <div className="mt-6 text-center">
                     <button
-                        onClick={handleUpload}
-                        disabled={loading}
-                        className={`progress-btn px-6 py-3 rounded-lg font-medium transition-colors ${
-                            loading
-                                ? 'bg-indigo-700 text-white cursor-not-allowed'
-                                : 'bg-indigo-600 text-white hover:bg-indigo-700'
-                        }`}
+                        onClick={() => { if (!loading) handleUpload(); }}
+                        className={`progress-btn px-6 py-3 rounded-lg font-medium ${loading ? 'is-loading' : 'hover:opacity-90'}`}
                     >
                         {loading && <div className="progress-fill" style={{ width: `${uploadProgress}%` }} />}
                         <span className="btn-content">