chore: project scaffold, build config, scripts and README

Bun + SvelteKit (static adapter) + Electron project files, icon resources,
dev/e2e/bench scripts and the README documenting the app.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

scripts/test-runner.cjs

@@ -0,0 +1,18 @@
+const { run } = require('node:test');
+const { spec } = require('node:test/reporters');
+const fs = require('fs');
+const path = require('path');
+const { app } = require('electron');
+
+app.whenReady().then(async () => {
+  const dir = path.join(__dirname, '../test');
+  const files = fs.readdirSync(dir)
+    .filter(f => f.endsWith('.test.js'))
+    .map(f => path.join(dir, f));
+  
+  const stream = run({ files });
+  stream.on('test:fail', () => { process.exitCode = 1; });
+  stream.compose(new spec()).pipe(process.stdout);
+  
+  stream.on('end', () => app.quit());
+});