Add generic state support to dioxus::server::router

[prodbyola]

Summary

This PR updates dioxus::server::router to return an axum::Router<S> with a generic state type instead of just axum::Router which takes () by default. This allows consumers to attach shared application state using Axum’s with_state pattern.

Motivation

Currently, there is no straightforward way to pass shared state (e.g. database pools, configuration, or services) into handlers when using dioxus::server::router. Since Dioxus server integration is built on top of Axum, enabling generic state aligns with standard Axum patterns and improves interoperability.

Changes

Updated router signature to:

pub fn router<S>(app: fn() -> Element) -> Router<S>
where
    S: Clone + Send + Sync + 'static

Preserved existing behavior while allowing callers to attach state via .with_state(...)

Example usage

dioxus::serve(|| async {
    let state = AppState::create().await.unwrap();

    Ok(
        dioxus::server::router(app)
            .with_state(state)
    )
});

Benefits

Enables clean dependency injection for server functions
Aligns with Axum’s standard state management model
Removes need for global state or workarounds like thread_local!
Improves ergonomics for real-world apps (e.g. SQLx, Redis, config)

Notes

No breaking changes for existing users who don’t use state
Type inference works seamlessly in most cases

Happy to adjust