Rust SDK: Generate method signatures for all endpoints

[iamnamananand996]

Description

Generate all HTTP method signatures with proper types, ready for implementation.

Target Implementation

impl UsersClient {
    pub async fn get_user(&self, id: &UserId, options: Option<RequestOptions>) -> Result<User, ApiError> {
        todo!("Implement HTTP request")
    }
    
    pub async fn create_user(&self, request: CreateUserRequest, options: Option<RequestOptions>) -> Result<User, ApiError> {
        todo!("Implement HTTP request")
    }
    
    pub async fn list_users(&self, params: Option<ListUsersParams>, options: Option<RequestOptions>) -> Result<Vec<User>, ApiError> {
        todo!("Implement HTTP request")
    }
}