feat: add initial implementation of Kitchen CRM with authentication and dashboard features

- Create global styles and theme management
- Implement app shell layout with sidebar navigation
- Add authentication layout and pages for login and registration
- Develop dashboard page with placeholder content
- Introduce routing guards for guest-only and authenticated routes
- Set up Zustand for state management of authentication and theme
- Create API types and structures for CRM entities
- Configure Vite with PWA support and Tailwind CSS

frontend/public/manifest.webmanifest

@@ -0,0 +1,28 @@
+{
+  "name": "Kitchen CRM",
+  "short_name": "KitchenCRM",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#020617",
+  "theme_color": "#0f172a",
+  "description": "Multi-tenant mini CRM dashboard for organizations, deals, contacts, and analytics.",
+  "icons": [
+    {
+      "src": "/pwa-icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any"
+    },
+    {
+      "src": "/pwa-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/pwa-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any maskable"
+    }
+  ]
+}