polish(phase9): sparkline + badge motion and a11y

Sparkline: friendlier aria-label ("3 completed today. 14 total over
the last 7 days." rather than a numeric list), per-bar <title>
tooltips with absolute date + count, 30 ms stagger entrance via
scaleY animation. Badge: 180 ms opacity + translateY entrance on
mount; conditional render means each new badge re-fires the
animation. Both animations respect prefers-reduced-motion.

The earlier draft tabindex=0 on the SVG was correctly flagged by
svelte-check as noninteractive_tabindex; SVG role="img" + aria-label
is sufficient for SR navigation without putting it in the keyboard
tab order.

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

src/lib/pages/TasksPage.svelte

@@ -298,7 +298,7 @@
         >
           {#if todayCount() > 0}
             <span
-              class="text-[11px] text-text-tertiary"
+              class="text-[11px] text-text-tertiary badge-today"
               aria-label={`${todayCount()} ${todayCount() === 1 ? "task" : "tasks"} completed today`}
             >
               {todayCount()} today
@@ -689,3 +689,27 @@
     </div>
   </div>
 </div>
+
+<style>
+  /* Phase 9 polish: gentle entrance animation when the today-count
+     badge mounts (it is conditionally rendered, so each new render
+     re-fires the animation). prefers-reduced-motion disables. */
+  :global(.badge-today) {
+    animation: badge-pop 180ms ease both;
+  }
+  @media (prefers-reduced-motion: reduce) {
+    :global(.badge-today) {
+      animation: none;
+    }
+  }
+  @keyframes badge-pop {
+    from {
+      opacity: 0;
+      transform: translateY(2px);
+    }
+    to {
+      opacity: 1;
+      transform: translateY(0);
+    }
+  }
+</style>