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/Streak.svelte

@@ -0,0 +1,23 @@
+<script lang="ts">
+  import type { FxOf } from "../fx";
+  import { center } from "./geom";
+  let { fx }: { fx: FxOf<"streak"> } = $props();
+  const a = $derived(center(fx.from));
+  const b = $derived(center(fx.to));
+</script>
+
+<line x1={a.x} y1={a.y} x2={b.x} y2={b.y} class="streak" />
+
+<style>
+  .streak {
+    stroke: rgba(233, 225, 203, 0.85);
+    stroke-width: 5;
+    stroke-linecap: round;
+    stroke-dasharray: 14 9;
+    animation: streak-fade 0.55s ease-out forwards;
+  }
+  @keyframes streak-fade {
+    0% { opacity: 0.9; stroke-dashoffset: 46; }
+    100% { opacity: 0; stroke-dashoffset: 0; }
+  }
+</style>