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>

reports-app/frontend/src/assets/css/layout/navigation.css

@@ -41,7 +41,7 @@
 
 /* Hamburger Menu */
 .hamburger-btn {
-  display: none;
+  display: flex;
   flex-direction: column;
   justify-content: space-between;
   width: 24px;
@@ -254,10 +254,6 @@
 
 /* Mobile Navigation */
 @media (max-width: 768px) {
-  .hamburger-btn {
-    display: flex;
-  }
-
   .header-actions {
     gap: var(--space-sm);
   }