feat: Use nullish coalescing for default select values

Replaces `||` with `??` for more precise default value assignment in select components.

Also updates Vite config to set `base` to `/` and disable sourcemaps during build.

vite.config.ts

@@ -8,8 +8,10 @@ export default defineConfig({
   define: {
     'process.env': process.env
   },
+  base: '/',
   build: {
     outDir: 'dist',
     emptyOutDir: true,
+    sourcemap: false
   }
 });