chore: initialize Vite project with Automerge dependencies

Set up project scaffold for a P2P polling app:
- package.json with @automerge/vanillajs, automerge-repo, vite deps
- vite.config.js with wasm and top-level-await plugins required by Automerge
- pnpm-lock.yaml lockfile
- .gitignore excluding node_modules

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vite.config.js

@@ -0,0 +1,7 @@
+import { defineConfig } from 'vite'
+import wasm from 'vite-plugin-wasm'
+import topLevelAwait from 'vite-plugin-top-level-await'
+
+export default defineConfig({
+  plugins: [wasm(), topLevelAwait()]
+})