feat: configure API dev proxy and improve useApiFetch error handling

- Add Nitro devProxy for local proxying of api/v1 and uploads to the backend server
- Improve useApiFetch to dynamically clear auth state and navigate to login on 401/403 errors
- Automatically strip Content-Type headers for multipart FormData upload request bodies
- Add css rule to fix Bootstrap Italia navbar link border display
- Add ts-expect-error tag to avoid type checking issues with bootstrap-italia bundle loading

app/plugins/bootstrap-italia.client.ts

@@ -1,3 +1,4 @@
 export default defineNuxtPlugin(async (nuxtApp) => {
+  // @ts-expect-error
   await import('bootstrap-italia/dist/js/bootstrap-italia.bundle.min.js')
 })