🗑️ Remove unused imports, macros and fields

- Drop unnecessary `axum::extract::{Path(State)}` imports in config.rs and registry.rs
- Mark unused field `_position_sec` with `#[allow(dead_code)]`
- Add missing attribute to dead code struct
- Remove unused macros `add_action_arg!`, etc. and related types (`PlayerReport`)

pmowebrenderer/src/registry.rs

@@ -3,11 +3,6 @@
 //! Remplace `SessionManager` et `websocket.rs`. La session est maintenant liée
 //! au flux FLAC HTTP, pas à une connexion WebSocket.
 
-use axum::{
-    extract::{Path, State},
-    http::StatusCode,
-    response::IntoResponse,
-};
 use parking_lot::RwLock;
 use std::collections::HashMap;
 use std::sync::Arc;