style(ai-onboarding): styles for the prompt-overlay image strip

Adds .ai-onboarding-prompt-images thumbnail row styling used by the
onboarding review overlay when the iframe sends reference images
alongside a userPrompt.

Author: abose

src/styles/Extn-AIChatPanel.less

@@ -419,6 +419,48 @@
         }
     }
 
+    .ai-onboarding-prompt-images {
+        display: flex;
+        flex-wrap: wrap;
+        gap: 8px;
+        padding: 8px 12px;
+        border-top: 1px solid rgba(255, 255, 255, 0.06);
+        background: @bc-ai-input-bg;
+
+        .ai-image-thumb {
+            position: relative;
+
+            img {
+                display: block;
+                max-width: 64px;
+                max-height: 48px;
+                object-fit: cover;
+                border-radius: 4px;
+                border: 1px solid rgba(255, 255, 255, 0.12);
+                cursor: pointer;
+            }
+
+            .ai-image-remove {
+                position: absolute;
+                top: -6px;
+                right: -6px;
+                width: 18px;
+                height: 18px;
+                border-radius: 50%;
+                background: rgba(0, 0, 0, 0.7);
+                border: 1px solid rgba(255, 255, 255, 0.3);
+                color: #fff;
+                font-size: 11px;
+                line-height: 1;
+                padding: 0;
+                display: flex;
+                align-items: center;
+                justify-content: center;
+                cursor: pointer;
+            }
+        }
+    }
+
     .ai-onboarding-prompt-actions {
         display: flex;
         justify-content: flex-end;