Every flourish gets its own file, and a workshop to watch them in

The effects move out of Board.svelte into src/fx-sprites/ — one
component per flourish, markup and animation CSS together, so editing
the fireball means opening Fireball.svelte and nothing else. A
registry (index.ts) maps kind to sprite; Board renders through it.
The event mapping stays in fx.ts.

And a viewer: /?fx opens the Flourish Workshop — every sprite on a
labeled parchment tile, replaying on a 2.2-second beat. Under the dev
server, editing any sprite file hot-reloads the gallery mid-loop.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/fx-sprites/Shimmer.svelte

@@ -0,0 +1,25 @@
+<script lang="ts">
+  import type { FxOf } from "../fx";
+  import { center } from "./geom";
+  let { fx }: { fx: FxOf<"shimmer"> } = $props();
+  const c = $derived(center(fx.at));
+</script>
+
+<circle cx={c.x} cy={c.y} r="6" class="shimmer" />
+<circle cx={c.x} cy={c.y} r="6" class="shimmer late" />
+
+<style>
+  .shimmer {
+    transform-box: fill-box;
+    transform-origin: center;
+    fill: none;
+    stroke: #b48ae0;
+    stroke-width: 2.5;
+    animation: ring 0.6s ease-out forwards;
+  }
+  .shimmer.late { stroke: #e2c8ff; animation-delay: 0.18s; opacity: 0; }
+  @keyframes ring {
+    0% { opacity: 0.95; transform: scale(1); }
+    100% { opacity: 0; transform: scale(5); }
+  }
+</style>