[chore](trx-rs): resolve all compiler and clippy warnings

- trx-server/rig_handle: remove dead vchan_manager field (was set but
  never read after the virtual-channel refactor)
- trx-server/listener: remove now-missing vchan_manager initializer
- trx-server/main: remove vchan_manager_for_handle intermediates that
  only fed the dropped field
- trx-server/audio: suppress too_many_arguments on run_audio_listener
- trx-frontend-http/server: suppress too_many_arguments on build_server
- trx-core/vchan: update module doc comment to not reference the
  removed RigHandle::vchan_manager field

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-server/src/audio.rs

@@ -1774,6 +1774,7 @@ enum VChanCmd {
 }
 
 /// Run the audio TCP listener, accepting client connections.
+#[allow(clippy::too_many_arguments)]
 pub async fn run_audio_listener(
     addr: SocketAddr,
     rx_audio: broadcast::Sender<Bytes>,

src/trx-server/src/listener.rs

@@ -466,7 +466,6 @@ mod tests {
             rig_tx,
             state_rx,
             audio_port: 4531,
-            vchan_manager: None,
         };
         let mut map = HashMap::new();
         map.insert("default".to_string(), handle);

src/trx-server/src/main.rs

@@ -1021,11 +1021,6 @@ async fn main() -> DynResult<()> {
         );
         task_handles.extend(audio_handles);
 
-        #[cfg(feature = "soapysdr")]
-        let vchan_manager_for_handle = sdr_vchan_manager;
-        #[cfg(not(feature = "soapysdr"))]
-        let vchan_manager_for_handle: Option<trx_core::vchan::SharedVChanManager> = None;
-
         rig_handles.insert(
             rig_cfg.id.clone(),
             RigHandle {
@@ -1034,7 +1029,6 @@ async fn main() -> DynResult<()> {
                 rig_tx,
                 state_rx,
                 audio_port: rig_cfg.audio.port,
-                vchan_manager: vchan_manager_for_handle,
             },
         );
     }

src/trx-server/src/rig_handle.rs

@@ -6,7 +6,6 @@
 
 use tokio::sync::{mpsc, watch};
 
-use trx_core::vchan::SharedVChanManager;
 use trx_core::rig::request::RigRequest;
 use trx_core::rig::state::RigState;
 
@@ -25,6 +24,4 @@ pub struct RigHandle {
     pub state_rx: watch::Receiver<RigState>,
     /// Per-rig audio listener TCP port.
     pub audio_port: u16,
-    /// Virtual channel manager; `Some` only for SDR rigs.
-    pub vchan_manager: Option<SharedVChanManager>,
 }