Add WCAG 2.1 Level AA accessibility across all components

src/lib/components/FontSelector.svelte

@@ -52,13 +52,15 @@
   <div class="flex items-center justify-between">
     <div>
       <div class="text-[13px] text-white">Countdown font</div>
-      <div class="text-[11px] text-[#555]">
+      <div class="text-[11px] text-[#8a8a8a]">
         {value || "System default"}
       </div>
     </div>
     <button
       type="button"
-      class="rounded-lg border border-[#1a1a1a] bg-black px-3 py-1.5 text-[12px] text-[#666]
+      aria-expanded={expanded}
+      aria-label={expanded ? "Close font browser" : "Browse fonts"}
+      class="rounded-lg border border-[#1a1a1a] bg-black px-3 py-1.5 text-[12px] text-[#8a8a8a]
              transition-colors hover:border-[#333] hover:text-white"
       onclick={() => { expanded = !expanded; }}
     >
@@ -75,6 +77,8 @@
       {#each fonts as font}
         <button
           type="button"
+          aria-label="Select font: {font.label}"
+          aria-pressed={value === font.family}
           class="flex flex-col items-center gap-1.5 rounded-xl border p-3
                  transition-all duration-150
                  {value === font.family
@@ -88,7 +92,7 @@
           >
             25:00
           </span>
-          <span class="text-[9px] tracking-wider text-[#555] uppercase">
+          <span class="text-[9px] tracking-wider text-[#8a8a8a] uppercase">
             {font.label}
           </span>
         </button>