Fix four review findings: busy release, poison recovery, core.md errors, chat loop

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/bxctl/src/main.rs

@@ -245,8 +245,9 @@ fn run_interactive(opts: &Options) -> ExitCode {
                 }
             }
             Ok(Err(e)) => {
+                // A failed turn is reported and the loop goes on: the session still exists, so the
+                // next line resumes it.
                 eprintln!("bxctl: {e}");
-                return ExitCode::from(1);
             }
         }
     }