`@nuxt/auth` integration for Asgardeo

### Problem

Although **Asgardeo** supports standard OIDC flows and can technically be integrated with `@nuxt/auth` using a generic OpenID Connect strategy, there is no official provider available.

We are currently working on delivering an official JavaScript SDK (see: https://github.com/asgardeo/javascript/issues/350). While the SDK will provide a first-class integration experience, having a dedicated provider within the `@nuxt/auth` ecosystem is still valuable.

Without an official provider:

- Developers must manually configure OIDC endpoints.
- Token handling and PKCE setup require additional configuration.
- Implementations may vary across projects.
- There is no standardized, documented integration path for Nuxt users.

Other providers (e.g., Auth0) have first-class support in `@nuxt/auth`, making integration straightforward and consistent.

### Proposed Solution

Introduce an official **Asgardeo provider** for `@nuxt/auth`, following the existing provider implementation patterns.

Reference implementations:
- Example provider documentation: https://auth.nuxtjs.org/providers/auth0
- Provider source structure: https://github.com/nuxt-community/auth-module/tree/dev/src/providers

#### Proposed Capabilities

- OIDC-based authentication
- PKCE support
- Access token, ID token, and refresh token handling
- Automatic token refresh
- User profile retrieval via the `userinfo` endpoint
- Proper logout support (including federated logout if configured)

#### Example Configuration

```js
auth: {
strategies: {
asgardeo: {
clientId: '',
issuer: 'https://api.asgardeo.io/t/',
scope: ['openid', 'profile', 'email']
}
}
}
```

### Alternatives

N/A

### Please select the package issue is related to

other

### Version

N/A

### Reporter Checklist

- [x] I have searched the existing issues and this is not a duplicate.
- [x] I have provided all the necessary information.
- [x] I have verified the feature on the latest version of the package.

Inizia leggendo la struttura del codice sorgente del provider nel repository @nuxt/auth indicato e la documentazione del provider Auth0, quindi confronta questi pattern con questo repository SDK. Definisci il comportamento del provider Asgardeo per OIDC, PKCE, il refresh dei token, userinfo e il logout, e verifica che la configurazione documentata funzioni end-to-end.

Scritto dal modello di indicizzazione a partire dal testo della issue.