refactor(comparison): drop no-op displayChar mapping

The space→non-breaking-space swap guarded against a lone space collapsing
to zero width, but the line container now uses white-space: pre (inherited
by Character), so spaces keep their width. The derived had been reduced to
a space→space identity; render `char` directly.

src/widgets/ComparisonView/ui/Character/Character.svelte

@@ -34,7 +34,6 @@ const fontB = $derived(comparisonStore.fontB);
 let slot = $state<0 | 1>(0);
 let slotFonts = $state<[string, string]>(['', '']);
 
-const displayChar = $derived(char === ' ' ? ' ' : char);
 const targetFont = $derived(isPast ? fontA?.name ?? '' : fontB?.name ?? '');
 
 $effect(() => {
@@ -63,7 +62,7 @@ $effect(() => {
                 style:position={slot === s ? 'relative' : 'absolute'}
                 aria-hidden={slot !== s ? true : undefined}
             >
-                {displayChar}
+                {char}
             </span>
         {/each}
     </span>