fix: switch vite minifier from terser to esbuild

terser is not in package.json so vite fails at the minification step
after transforming all modules — the script exits non-zero, killing
the installer. esbuild is bundled with vite and requires no extra dep.

nixclient/vite.config.ts

@@ -6,7 +6,7 @@ export default defineConfig({
   build: {
     outDir: 'dist',
     sourcemap: false,
-    minify: 'terser',
+    minify: 'esbuild',
   },
   server: {
     port: 3001,

nixserver/vite.config.ts

@@ -6,7 +6,7 @@ export default defineConfig({
   build: {
     outDir: 'dist',
     sourcemap: false,
-    minify: 'terser',
+    minify: 'esbuild',
   },
   server: {
     port: 3000,