feat!: upgrade to SvelteKit 3 and adapter-bun

- run sv migrate sveltekit-3: config moves into vite.config.ts, $lib becomes
  #lib, $env/dynamic becomes $app/env/private via src/env.ts, $app/environment
  becomes $app/env, hook types move to @sveltejs/kit/hooks
- env vars stay optional (the migrator defaulted them to ''), and BANCHO_MODE,
  which it missed, is declared and passed to simulatorEnabled
- handleError only logs and masks unknown errors; Kit 3 now routes 404s and
  error(...) through it too
- json()/text() become Response.json()/new Response(); goto keepFocus/noScroll
  becomes reset: false; invalidateAll becomes refreshAll; page.url is copied
  before mutating
- replace adapter-node with @sveltejs/adapter-bun; prod-server.ts wraps
  Bun.serve to add native WebSockets (bunSockets) for /ws paths, since the
  generated server has no websocket option
- drop the Kit readdir patch: Kit 3 sorts route entries itself
- match view and broadcast pages use the live score modules

BREAKING CHANGE: requires SvelteKit 3, TypeScript 6 and Bun 1.4; the build
output is build/index.js from adapter-bun, started through prod-server.ts.

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

prod-server.ts

@@ -1,11 +1,13 @@
-import { createServer } from 'node:http';
-import { handler } from './build/handler.js';
-import { attachSockets } from './src/lib/server/ws-attach.ts';
+/**
+ * Production entry: the server adapter-bun generates, plus the app's WebSockets.
+ * The generated server calls Bun.serve itself and has no websocket option, so
+ * Bun.serve is wrapped before it loads to upgrade /ws paths first. Everything
+ * else (static assets, HOST/PORT/*_HEADER env, graceful shutdown) is the adapter's.
+ */
+import { bunSockets } from './src/lib/server/ws-attach.ts';
 
-const port = Number(process.env.PORT || 3000);
-const host = process.env.HOST || '0.0.0.0';
-const server = createServer(handler);
-await attachSockets(server);
-server.listen(port, host, () => {
-	console.log(`Vash Esports listening on ${host}:${port}`);
-});
+const serve = Bun.serve;
+Bun.serve = ((options: Parameters<typeof serve>[0] & { fetch: Parameters<typeof bunSockets>[0] }) =>
+	serve({ ...options, ...bunSockets(options.fetch) })) as typeof serve;
+
+await import('./build/index.js');