Phase 1: scaffold + metronome engine + R1

Svelte 5 + Vite static SPA with absolute base and History-API path routing.
Core lookahead-scheduler metronome (no drift), AudioContext unlock-on-gesture,
synthesized 3-voice clicks, rAF-synced beat highlight. StrumGrid renderer and
R1 wired end-to-end with variants, BPM/variant persistence, query overrides,
and keyboard shortcuts (space, arrow up/down). Dark amp-light theme tokens.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

vite.config.ts

@@ -0,0 +1,16 @@
+import { defineConfig } from 'vite'
+import { svelte } from '@sveltejs/vite-plugin-svelte'
+
+// Base path is absolute so nested path-routed URLs (e.g. /practice/drill/R3)
+// resolve hashed asset URLs correctly. Use '/' for a dedicated domain, or set
+// VITE_BASE=/practice/ at build time for a subpath deploy.
+// (Relative base './' would break assets on nested routes — do not use it here.)
+const base = process.env.VITE_BASE ?? '/'
+
+export default defineConfig({
+  base,
+  plugins: [svelte()],
+  build: {
+    target: 'es2020',
+  },
+})