[style](trx-core): improve code formatting and trait readability

Reformat filter state methods and error handling for better consistency.
Improve readability of complex return type expressions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/trx-core/src/lib.rs

@@ -10,8 +10,8 @@ pub mod rig;
 
 pub type DynResult<T> = Result<T, Box<dyn std::error::Error + Send + Sync>>;
 
-pub use rig::AudioSource;
 pub use rig::command::RigCommand;
 pub use rig::request::RigRequest;
 pub use rig::response::{RigError, RigResult};
 pub use rig::state::{RigFilterState, RigMode, RigSnapshot, RigState};
+pub use rig::AudioSource;

src/trx-core/src/rig/mod.rs

@@ -121,28 +121,34 @@ pub trait RigCat: Rig + Send {
 
     fn unlock<'a>(&'a mut self) -> Pin<Box<dyn Future<Output = DynResult<()>> + Send + 'a>>;
 
-    fn as_audio_source(&self) -> Option<&dyn AudioSource> { None }
+    fn as_audio_source(&self) -> Option<&dyn AudioSource> {
+        None
+    }
 
     fn set_bandwidth<'a>(
         &'a mut self,
         _bandwidth_hz: u32,
     ) -> Pin<Box<dyn Future<Output = DynResult<()>> + Send + 'a>> {
-        Box::pin(std::future::ready(Err(Box::new(
-            response::RigError::not_supported("set_bandwidth"),
-        ) as Box<dyn std::error::Error + Send + Sync>)))
+        Box::pin(std::future::ready(Err(
+            Box::new(response::RigError::not_supported("set_bandwidth"))
+                as Box<dyn std::error::Error + Send + Sync>,
+        )))
     }
 
     fn set_fir_taps<'a>(
         &'a mut self,
         _taps: u32,
     ) -> Pin<Box<dyn Future<Output = DynResult<()>> + Send + 'a>> {
-        Box::pin(std::future::ready(Err(Box::new(
-            response::RigError::not_supported("set_fir_taps"),
-        ) as Box<dyn std::error::Error + Send + Sync>)))
+        Box::pin(std::future::ready(Err(
+            Box::new(response::RigError::not_supported("set_fir_taps"))
+                as Box<dyn std::error::Error + Send + Sync>,
+        )))
     }
 
     /// Return the current filter state if this backend supports filter controls.
-    fn filter_state(&self) -> Option<state::RigFilterState> { None }
+    fn filter_state(&self) -> Option<state::RigFilterState> {
+        None
+    }
 }
 
 /// Snapshot of a rig's status that every backend can expose.