style(sidecar): apply rustfmt

Format the sidecar source with `cargo fmt` so the new `cargo fmt --check`
CI gate passes on the first run. No behavior change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0114TpmrNW4wNXsHq5CR72jQ

sidecar/src/rpc.rs

@@ -56,10 +56,7 @@ impl Rpc {
     ) -> Result<Value, RpcError> {
         let (tx, rx) = oneshot::channel();
 
-        self.pending
-            .lock()
-            .await
-            .insert(corr_val.to_string(), tx);
+        self.pending.lock().await.insert(corr_val.to_string(), tx);
 
         if !shard.send(command.to_string()).await {
             self.pending.lock().await.remove(corr_val);