Enable source maps for production builds

Adds sourcemap: true to Vite build configuration to generate external source map files (.map) alongside JavaScript bundles. This enables debugging of production builds with original source code while keeping source maps separate from the main bundle files.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src-web/vite.config.ts

@@ -39,6 +39,7 @@ export default defineConfig(async () => {
     }),
   ],
   build: {
+    sourcemap: true,
     outDir: '../dist',
     emptyOutDir: true,
     rollupOptions: {