fix: copy static assets into standalone dir after next build

next build with output:standalone does not automatically copy
.next/static or public into .next/standalone/. The standalone
server.js looks for them at __dirname/.next/static and
__dirname/public, so they must be copied there post-build.

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

package.json

@@ -4,7 +4,7 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "build": "next build",
+    "build": "next build && cp -r .next/static .next/standalone/.next/static && cp -r public .next/standalone/public",
     "check": "eslint . && tsc --noEmit",
     "db:generate": "drizzle-kit generate",
     "db:migrate": "bun src/server/db/migrate.ts",