fix: Resolve shared component styling and Vite module deduplication

- Add dedupe option for vue, vue-router, pinia, primevue in both Vite configs
  to prevent duplicate module issues when using shared components
- Add optimizeDeps and commonjsOptions for better shared module handling
- Fix CompanySelector and PeriodSelector header variants to support both
  light headers (using CSS variables) and gradient headers (white text)
- Make hamburger button always display:flex for consistent mobile layout

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

data-entry-app/frontend/vite.config.js

@@ -10,7 +10,8 @@ export default defineConfig({
     alias: {
       '@': fileURLToPath(new URL('./src', import.meta.url)),
       '@shared': fileURLToPath(new URL('../../shared', import.meta.url))
-    }
+    },
+    dedupe: ['vue', 'vue-router', 'pinia', 'primevue']
   },
   server: {
     port: 3010,