a11y: final cleanup -- remaining hardcoded colors

- FontSelector: text-[#8a8a8a]→text-text-sec, border-[#222]→border-border
- StatsView: Canvas fillStyle and inline trend color #8a8a8a→#a8a8a8
- ActivityManager: border-[#222]→border-border, #f85149→#ff6b6b danger color
- Settings: #f85149→#ff6b6b danger color on reset/delete buttons

src/lib/components/FontSelector.svelte

@@ -52,7 +52,7 @@
   <div class="flex items-center justify-between">
     <div>
       <div class="text-[13px] text-white">Countdown font</div>
-      <div class="text-[11px] text-[#8a8a8a]">
+      <div class="text-[11px] text-text-sec">
         {value || "System default"}
       </div>
     </div>
@@ -60,7 +60,7 @@
       type="button"
       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]
+      class="rounded-lg border border-[#1a1a1a] bg-black px-3 py-1.5 text-[12px] text-text-sec
              transition-colors hover:border-[#333] hover:text-white"
       onclick={() => { expanded = !expanded; }}
     >
@@ -83,7 +83,7 @@
                  transition-all duration-150
                  {value === font.family
                    ? 'border-white/30 bg-[#141414]'
-                   : 'border-[#141414] bg-[#0a0a0a] hover:border-[#222] hover:bg-[#0f0f0f]'}"
+                   : 'border-[#141414] bg-[#0a0a0a] hover:border-border hover:bg-[#0f0f0f]'}"
           onclick={() => selectFont(font.family)}
         >
           <span
@@ -92,7 +92,7 @@
           >
             25:00
           </span>
-          <span class="text-[9px] tracking-wider text-[#8a8a8a] uppercase">
+          <span class="text-[9px] tracking-wider text-text-sec uppercase">
             {font.label}
           </span>
         </button>