feat(confidence-engine): clarify understanding during Done refresh

app/globals.css

@@ -24,6 +24,50 @@
   animation-delay: 0.16s;
 }
 
+/* ── CU skeleton overlay during synthesis refresh ─────────────── */
+
+.cu-skeleton-overlay {
+  pointer-events: none;
+}
+
+.cu-skeleton-lines {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  width: 100%;
+  margin-top: auto;
+}
+
+.cu-skeleton-line {
+  height: 16px;
+  border-radius: 8px;
+  background-color: #e5e7eb;
+  position: relative;
+  overflow: hidden;
+}
+
+/* Striped shimmer that travels left → right through each bar */
+.cu-skeleton-line::after {
+  content: "";
+  position: absolute;
+  inset: 0;
+  background: repeating-linear-gradient(
+    105deg,
+    transparent 0%,
+    transparent 8px,
+    rgba(255, 255, 255, 0.45) 8px,
+    rgba(255, 255, 255, 0.45) 16px,
+    transparent 16px,
+    transparent 24px
+  );
+  animation: cuSkeletonShimmer 1.6s linear infinite;
+}
+
+@keyframes cuSkeletonShimmer {
+  0%   { transform: translateX(-100%); }
+  100% { transform: translateX(100%); }
+}
+
 @media (prefers-reduced-motion: reduce) {
   [style*="animation:spin"] {
     animation: none !important;
@@ -32,4 +76,8 @@
   .investigation-card {
     animation: none;
   }
+
+  .cu-skeleton-line::after {
+    animation: none !important;
+  }
 }