feat(settings): add settings page with server, watchdog and notification config

- Add new Settings view with form controls for server, watchdog and notification settings
- Implement API endpoints for getting and saving settings
- Add settings route and sidebar navigation item
- Update button styles to include text color variable
- Change default app target to local development address

src/router/index.js

@@ -54,6 +54,12 @@ const routes = [
                 name: 'SystemInfo',
                 component: () => import('../views/SystemInfo.vue'),
                 meta: { requiresAuth: true }
+            },
+            {
+                path: 'settings',
+                name: 'Settings',
+                component: () => import('../views/Settings.vue'),
+                meta: { requiresAuth: true, permission: ['superuser', 'admin'] }
             }
         ]
     }