Improve showcase pages: drawers, modals, badges, and Vite caching fix

- DTDrawer: storefront-matching dual-element bevel border, slide-in/out
  animations from correct edge, 99vh height, bold 2em header, box shadow
- DTModal: interactive demos on Bevels page with all 5 mode variants
- Badges: solid color fill with contrasting text (black on dark, white on light)
  instead of transparent fill with colored text
- Animations: add dt-slide-right and dt-slide-left keyframes for drawers
- Bevels page: remove trash "Button Bevels", add interactive modal/drawer
  demos, fix media frame to use real images with proper bevel styling
- Advanced Cards: remove redundant media frame sections, rename "Menu Items"
  to "Buttons", remove DTButton/dt-btn references
- Forms page: rename "Menu Items" to "Buttons"
- Vite config: exclude design system packages from optimizeDeps pre-bundling
  and watch dist directories to prevent stale CSS during development

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/showcase/desktop/vite.config.ts

@@ -15,4 +15,16 @@ export default defineConfig({
       '@dangerousthings/web': path.resolve(__dirname, '../../web/dist'),
     },
   },
+  optimizeDeps: {
+    // Don't pre-bundle design system packages — they're local workspace deps
+    // that change frequently during development. Pre-bundling caches them in
+    // node_modules/.vite which causes stale CSS/JS after rebuilds.
+    exclude: ['@dangerousthings/web', '@dangerousthings/react', '@dangerousthings/tokens'],
+  },
+  server: {
+    // Watch design system dist directories for changes during dev
+    watch: {
+      ignored: ['!**/packages/web/dist/**', '!**/packages/react/dist/**', '!**/packages/tokens/dist/**'],
+    },
+  },
 });