fix(ui): viewer modal — haze background through to the image, fit-to-view at zoom 1

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/modal/VideoCanvas.vue

@@ -34,7 +34,9 @@ const playable = computed(() => BROWSER_PLAYABLE.has(props.mime))
 <style scoped>
 .fc-canvas {
   flex: 1;
-  background: rgb(var(--v-theme-background));
+  /* Transparent so the viewer's haze shows through (parallels
+     ImageCanvas — both sit inside ImageViewer's blurred backdrop). */
+  background: transparent;
   display: flex; align-items: center; justify-content: center;
 }
 .fc-canvas__video { max-width: 100%; max-height: 100%; }