Make Electron build

I historically have never liked Electron, and I don't like it now, but
unfortunately due to poor browser support, I don't have a choice to
ship anything more lightweight if I want to use the Filesystem API
as part of the packaged build, which is kind of the point.

I guess it's true:
"You either die a hero or you live long enough to become the villain."

This is an experimental build.

electron/copy-dist.mjs

@@ -0,0 +1,16 @@
+import { cpSync, rmSync, existsSync } from 'node:fs';
+import { join, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const dir = dirname(fileURLToPath(import.meta.url));
+const src = join(dir, '..', 'web', 'dist');
+const dst = join(dir, 'dist');
+
+if (!existsSync(src)) {
+    console.error('web/dist/ does not exist — run "cd web && npm run build" first.');
+    process.exit(1);
+}
+
+rmSync(dst, { recursive: true, force: true });
+cpSync(src, dst, { recursive: true });
+console.log(`Copied ${src} -> ${dst}`);