fix(web): split chart chunk with rolldown codeSplitting

Vite 8 uses Rolldown, which rejects the object form of manualChunks.
Move the chart.js chunk to build.rolldownOptions.output.codeSplitting.

web/vite.config.js

@@ -14,10 +14,15 @@ export default defineConfig({
     outDir: 'dist',
     assetsDir: 'assets',
     emptyOutDir: true,
-    rollupOptions: {
+    rolldownOptions: {
       output: {
-        manualChunks: {
+        codeSplitting: {
-          'chart': ['chart.js']
+          groups: [
+            {
+              name: 'chart',
+              test: /node_modules\/(chart\.js|@kurkle\/color)\//
+            }
+          ]
         }
       }
     }