refactor: inline reader thread handle in _read_agent_stream

The `reader` local served only to call `.start()` — the thread is
never joined explicitly because termination is signalled through the
queue's None sentinel and the daemon flag.  Collapsing into the
fluent `Thread(...).start()` form matches the fire-and-forget intent
and drops an unused binding.

Python's `threading` module keeps live threads reachable via
`threading._active`, so dropping the local reference does not affect
thread lifetime.

Co-authored-by: Ralphify <noreply@ralphify.co>

Author: 2 people

src/ralphify/_agent.py

@@ -342,8 +342,7 @@ def _read_agent_stream(
     result_text: str | None = None
 
     line_q: queue.Queue[str | None] = queue.Queue()
-    reader = threading.Thread(target=_readline_pump, args=(stdout, line_q), daemon=True)
-    reader.start()
+    threading.Thread(target=_readline_pump, args=(stdout, line_q), daemon=True).start()
 
     while True:
         # Compute how long we can wait for the next line.