* fix: Handle HTTP errors in FromResponseParts
Check for non-success status codes before attempting to decode response
parts. For error responses, parse the JSON error payload and convert it
to a ServerFnError::ServerError.
Also make ErrorPayload fields pub(crate) to allow internal access.
* fixed test name
overhaul dioxus fullstack using a new implementation of server_fn
This PR is a complete rewrite of dioxus fullstack designed to improve compatibility with axum and to fix a number of compilation errors based on feature flag unification plumbing through macros.