fix(voice): import ActivationMode in non-macOS dictation listener

start_rdev_listener (cfg not(target_os = "macos")) maps
DictationActivationMode into the hotkey ActivationMode, but the type was
never imported — so cargo clippy/build fails on Linux with
"cannot find type ActivationMode". macOS was unaffected because the
function is cfg'd out there. Add a cfg-gated use matching the only cfg
that references the type (no unused-import warning on macOS).

Author: YOMXXX

src/openhuman/voice/dictation_listener.rs

@@ -13,6 +13,10 @@ use tokio::sync::broadcast;
 use tokio::task::JoinHandle;
 
 use crate::openhuman::config::Config;
+// Only `start_rdev_listener` (non-macOS) maps into the hotkey `ActivationMode`,
+// so gate the import to the same cfg to avoid an unused-import warning on macOS.
+#[cfg(not(target_os = "macos"))]
+use crate::openhuman::voice::hotkey::ActivationMode;
 
 const LOG_PREFIX: &str = "[dictation_listener]";