chore: fix unused import and suppress dead_code for reserved protocol items

Remove `warn` from keyboard.rs imports — it was never called there.

Add #![allow(dead_code)] to protocol.rs since that module intentionally
defines the full shared protocol up-front, including constants and
constructors reserved for future features (numpad, active-app, ACK,
FLAG_RESPONSE). Suppressing at the module level is cleaner than
annotating each item individually.

src/keyboard.rs

@@ -15,7 +15,7 @@ use std::time::Duration;
 
 use anyhow::{Context, Result};
 use hidapi::HidApi;
-use log::{debug, error, info, trace, warn};
+use log::{debug, error, info, trace};
 
 use crate::protocol::{Packet, PACKET_SIZE, USAGE_ID, USAGE_PAGE};
 

src/protocol.rs

@@ -1,6 +1,12 @@
 // Copyright 2026 rootiest
 // SPDX-License-Identifier: GPL-3.0-or-later
 
+// This module defines the complete shared protocol including constants and
+// constructors reserved for future features (numpad, active-app, ACK).
+// Suppressing dead_code here is intentional — these items will be used once
+// the corresponding firmware and host features are implemented.
+#![allow(dead_code)]
+
 //! Shared Raw HID packet protocol.
 //!
 //! All constants and layout MUST match `hid_protocol.h` in the QMK keymap.