Implement authentication phase with Cidaas OAuth2 integration

- Add authentication middleware to protect routes
- Create API endpoints for login, logout, registration, and user info
- Develop UI components for login and registration forms
- Integrate VeeValidate for form validation
- Update environment configuration for Cidaas settings
- Add i18n support for English and German languages
- Enhance Tailwind CSS for improved styling of auth components
- Document authentication flow and testing procedures

app/components/ui/alert/index.ts

@@ -0,0 +1,24 @@
+import type { VariantProps } from 'class-variance-authority'
+import { cva } from 'class-variance-authority'
+
+export { default as Alert } from './Alert.vue'
+export { default as AlertDescription } from './AlertDescription.vue'
+export { default as AlertTitle } from './AlertTitle.vue'
+
+export const alertVariants = cva(
+  'relative w-full rounded-lg border p-4 [&>svg~*]:pl-7 [&>svg+div]:translate-y-[-3px] [&>svg]:absolute [&>svg]:left-4 [&>svg]:top-4 [&>svg]:text-foreground',
+  {
+    variants: {
+      variant: {
+        default: 'bg-background text-foreground',
+        destructive:
+          'border-destructive/50 text-destructive dark:border-destructive [&>svg]:text-destructive',
+      },
+    },
+    defaultVariants: {
+      variant: 'default',
+    },
+  }
+)
+
+export type AlertVariants = VariantProps<typeof alertVariants>