Fix BboxOverlay inline handler breaking production build

Vue template compiler in production mode rejects multi-statement
inline handlers without semicolons. Extract to a named function.

frontend/src/features/analysis/ui/BboxOverlay.vue

@@ -20,10 +20,7 @@
       ref="canvasRef"
       class="overlay-canvas"
       @mousemove="onMouseMove"
-      @mouseleave="
-        hoveredElement = null
-        emit('highlight-element', -1)
-      "
+      @mouseleave="onMouseLeave"
     />
     <div v-if="hoveredElement" class="tooltip" :style="tooltipStyle">
       <span
@@ -158,6 +155,11 @@ function draw(): void {
   }
 }
 
+function onMouseLeave(): void {
+  hoveredElement.value = null
+  emit('highlight-element', -1)
+}
+
 function onMouseMove(e: MouseEvent): void {
   const canvas = canvasRef.value
   const img = props.imageEl