Add experiments folder. Add usage.md and SKILL.md. Fix Sheet interactions and add dynamic sheet mode.

vitest.config.ts

@@ -1,6 +1,10 @@
+import vue from "@vitejs/plugin-vue";
 import { defineConfig } from "vitest/config";
 
 export default defineConfig({
+  // Vitest 3 carries Vite 6 types while this workspace builds with Vite 8.
+  // The plugin is runtime-compatible; remove this cast when Vitest is upgraded.
+  plugins: [vue() as never],
   test: {
     environment: "happy-dom",
     include: ["packages/**/*.test.ts"],