fix: suppress Rust compiler warnings in buttplug

- #[allow(dead_code)] on FFICallbackContextWrapper, Connected variant,
  Unsubscribe variant, and device_event_receiver field
- let _ = for unused Result from callback.call1() (x2) and .send().await

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

packages/buttplug/src/lib.rs

@@ -23,6 +23,7 @@ type FFICallback = js_sys::Function;
 type FFICallbackContext = u32;
 
 #[derive(Clone, Copy)]
+#[allow(dead_code)]
 pub struct FFICallbackContextWrapper(FFICallbackContext);
 
 unsafe impl Send for FFICallbackContextWrapper {
@@ -50,7 +51,7 @@ pub fn send_server_message(
     let buf = json.as_bytes();
     let this = JsValue::null();
     let uint8buf = unsafe { Uint8Array::new(&Uint8Array::view(buf)) };
-    callback.call1(&this, &JsValue::from(uint8buf));
+    let _ = callback.call1(&this, &JsValue::from(uint8buf));
   }
 }
 
@@ -119,7 +120,7 @@ pub fn buttplug_client_send_json_message(
       let buf = json.as_bytes();
       let this = JsValue::null();
       let uint8buf = unsafe { Uint8Array::new(&Uint8Array::view(buf)) };
-      callback.call1(&this, &JsValue::from(uint8buf));
+      let _ = callback.call1(&this, &JsValue::from(uint8buf));
     }
   });
 }