fix(storybook): hold the Storybook build to the app's chunk-size ceiling

The panel build allows 1500 kB chunks, but the Storybook build kept Vite's
500 kB default, so every build warned about the bundled UI and the axe engine
from the accessibility addon.

frontend/.storybook/main.ts

@@ -15,6 +15,8 @@ const config: StorybookConfig = {
     if (viteConfig.build) {
       viteConfig.build.outDir = undefined;
       viteConfig.build.emptyOutDir = false;
+      // Storybook bundles the whole UI plus the axe engine; hold it to the app's chunk ceiling.
+      viteConfig.build.chunkSizeWarningLimit = 1500;
       if (viteConfig.build.rollupOptions) {
         viteConfig.build.rollupOptions.input = undefined;
       }