Fix crash when running without --flight flag and Unicode crash on Windows

- fly_embodied.py: fly_name was only assigned inside the `if args.flight`
  block but used unconditionally by the proboscis joint lookup. Added
  fly_name = fly.name before the proboscis section.
- benchmark.py: replaced Unicode checkmark/cross (U+2713/U+2717) with
  ASCII "OK"/"FAIL" to prevent encoding crash on Windows consoles.

code/benchmark.py

@@ -217,7 +217,7 @@ def print_summary_table(all_results, backend_name, logger):
 
     for result in all_results:
         t = result.get('timings', {})
-        status_icon = "\u2713" if result['status'] == 'success' else "\u2717"
+        status_icon = "OK" if result['status'] == 'success' else "FAIL"
 
         setup_time = t.get(
             'network_creation_total', t.get('model_setup_total', 0)

fly_embodied.py

@@ -429,6 +429,7 @@ def main():
 
     # ── Find proboscis joint (added dynamically to Rostrum) ──
     model_ptr = sim.physics.model.ptr
+    fly_name = fly.name
     for jname_candidate in [f"{fly_name}/joint_Proboscis", "joint_Proboscis"]:
         proboscis_jnt_id = mujoco.mj_name2id(
             model_ptr, mujoco.mjtObj.mjOBJ_JOINT, jname_candidate)