Fix P1 Rust: use dd0c_route:: instead of crate:: in binary imports, add hex crate

Binary targets (api, proxy, worker) can't use crate:: to access lib modules.
Must reference the library crate name dd0c_route:: instead.

products/01-llm-cost-router/src/api/handler.rs

@@ -9,8 +9,8 @@ use serde::{Deserialize, Serialize};
 use std::sync::Arc;
 use uuid::Uuid;
 
-use crate::auth::{AuthContext, AuthError, AuthProvider, Role};
-use crate::config::AppConfig;
+use dd0c_route::auth::{AuthContext, AuthError, AuthProvider, Role};
+use dd0c_route::config::AppConfig;
 
 pub struct ApiState {
     pub auth: Arc<dyn AuthProvider>,