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/StatsView.svelte

@@ -156,7 +156,7 @@
 
       // Day label — show every Nth for 30-day
       if (data.length <= 7 || i % 5 === 0) {
-        ctx.fillStyle = "#8a8a8a";
+        ctx.fillStyle = "#a8a8a8";
         ctx.font = "10px -apple-system, sans-serif";
         ctx.textAlign = "center";
         const label = day.date.slice(5);
@@ -508,7 +508,7 @@
             <span class="text-text-sec">Avg {week.avgDailyCompleted.toFixed(1)} breaks/day</span>
             {#if prevWeek}
               <span class="flex items-center gap-1"
-                style="color: {trend > 0 ? '#3fb950' : trend < 0 ? '#f85149' : '#8a8a8a'};"
+                style="color: {trend > 0 ? '#3fb950' : trend < 0 ? '#ff6b6b' : '#a8a8a8'};"
               >
                 {#if trend > 0}
                   <svg width="10" height="10" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="3"><path d="M18 15l-6-6-6 6"/></svg>