fix: polish initial flipbook reveal and update third-party metadata

public/assets/flipbook-module.css

@@ -13,11 +13,24 @@
 }
 
 .mod-pdf-flipbook__status {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.55rem;
     margin-bottom: 0.8rem;
     font-size: 0.92rem;
     color: var(--flipbook-text);
 }
 
+.mod-pdf-flipbook__status::before {
+    content: '';
+    width: 0.9rem;
+    height: 0.9rem;
+    border: 2px solid rgba(48, 45, 41, 0.25);
+    border-top-color: rgba(48, 45, 41, 0.85);
+    border-radius: 50%;
+    animation: mod-pdf-flipbook-spin 0.75s linear infinite;
+}
+
 .mod-pdf-flipbook__status.is-hidden {
     display: none;
 }
@@ -26,18 +39,29 @@
     color: #9f1f1f;
 }
 
+.mod-pdf-flipbook__status.is-error::before {
+    display: none;
+}
+
 .mod-pdf-flipbook__stage {
     position: relative;
     width: 100%;
     margin: 0 auto;
     background: #e0e0e0;
     z-index: 1;
+    transition: opacity 1.3s ease 0.5s;
 }
 
 .mod-pdf-flipbook .c-flipbook {
     max-width: 100%;
 }
 
+.mod-pdf-flipbook .c-flipbook.is-booting,
+.mod-pdf-flipbook .c-flipbook.is-booting .c-flipbook__page,
+.mod-pdf-flipbook .c-flipbook.is-booting .c-flipbook__page::before {
+    transition: none !important;
+}
+
 .mod-pdf-flipbook .c-flipbook__page {
     background: #fefdf9;
     overflow: hidden;
@@ -73,6 +97,7 @@
     display: flex;
     gap: 0.6rem;
     margin-top: 0.9rem;
+    transition: opacity 1.3s ease 0.5s;
 }
 
 .mod-pdf-flipbook__error {
@@ -85,3 +110,9 @@
         justify-content: space-between;
     }
 }
+
+@keyframes mod-pdf-flipbook-spin {
+    to {
+        transform: rotate(360deg);
+    }
+}