[feat](trx-client): default to port 4532 when not specified in URL

Allow connecting with just an IP address (e.g. --url 127.0.0.1)
instead of requiring host:port format.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-client/src/remote_client.rs

@@ -195,7 +195,7 @@ pub fn parse_remote_url(url: &str) -> Result<String, String> {
         .unwrap_or(trimmed);
 
     if !addr.contains(':') {
-        return Err("remote url must be host:port".into());
+        return Ok(format!("{}:4532", addr));
     }
 
     Ok(addr.to_string())