feat: Frontend CSS refactoring and test improvements

Frontend:
- Refactored CSS architecture with new utility classes
- Updated dashboard components styling
- Improved responsive grid system
- Enhanced typography and variables
- Updated E2E and integration tests

Added:
- Claude Code slash commands for validation
- SSH tunnel and start test scripts

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

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

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

@@ -254,23 +254,23 @@
   .hamburger-btn {
     display: flex;
   }
-  
+
   .header-actions {
     gap: var(--space-sm);
   }
-  
+
   .quick-actions {
     display: none;
   }
-  
+
   .slide-menu {
     width: 280px;
   }
-  
+
   .menu-section {
     padding: var(--space-md);
   }
-  
+
   .quick-action-btn {
     justify-content: center;
     padding: var(--space-md);
@@ -281,9 +281,9 @@
   .header-brand {
     font-size: var(--text-base);
   }
-  
+
   .slide-menu {
     width: 100vw;
     max-width: 320px;
   }
-}
+}