test_refinement_mrt: check force reads in executable text, not comments

The block_collision.cuh header comment names the absent d_params.fx/fy
read, which tripped the source-text assertion. Strip // comments first
and also require the real d_params.omega read. Test-only; no kernel source
change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/test_refinement_mrt.py

@@ -1,5 +1,6 @@
 """Host guards and source contract for MRT reuse in refined/blocked stepping (no CUDA)."""
 from pathlib import Path
+import re
 import unittest
 
 from CelerisLab.config import LBMConfig
@@ -34,8 +35,11 @@ class RefinementMRTHost(unittest.TestCase):
         self.assertIn("collide_srt(f, feq, forcing, omega);", block_collision)
         self.assertIn("#if COLLISION_MODEL == 2 || BLOCK_ROOT_BC == 2", block_collision)
         self.assertEqual(channel.count("block_collide(f);"), 1)
+        # Executable text only: the header comment explains the absent force read.
+        code = re.sub(r"//[^\n]*", "", channel + "\n" + block_collision)
+        self.assertIn("d_params.omega", code)
         for text in ("collide_mrt_unforced", "collide_dispatch(", "d_params.fx", "d_params.fy"):
-            self.assertNotIn(text, channel + "\n" + block_collision)
+            self.assertNotIn(text, code)
         for source in (blocks,):
             self.assertIn("(COLLISION_MODEL != 0 && COLLISION_MODEL != 2)", source)
             self.assertIn("USE_LES", source)