Fix dangerous pkill, circular import, and dedup _res_suffix

- Scope pkill to 'pdal pipeline' (avoids killing unrelated PDAL jobs)
- Inline _strip_lidar_ext in dtm.py to remove circular import from pipeline
- _res_suffix_str now delegates to LidarArchaeoPipeline._res_suffix

lidar_pipeline/dtm.py

@@ -31,6 +31,15 @@ IGN_CLASS_NAMES = {
 }
 
 
+def _strip_lidar_ext(path):
+    """Extract base name from a LAZ/LAS file (mirrors pipeline._file_basename)."""
+    name = Path(path).name
+    for ext in ('.copc.laz', '.copc.las', '.laz', '.las'):
+        if name.lower().endswith(ext):
+            return name[:-len(ext)]
+    return Path(path).stem
+
+
 def parse_ign_classes(spec):
     """Convertit une liste de classes IGN (noms ou codes) en codes LAS triés.
 
@@ -462,9 +471,7 @@ def classify_ground(laz_file, temp_dir, method='auto', force=False, ign_classes=
     ign_codes = parse_ign_classes(ign_classes) if method == 'ign' else None
     method_label = ign_method_label(ign_codes) if ign_codes else method
 
-    # Use shared basename extraction function
-    from .pipeline import _file_basename
-    laz_base = _file_basename(laz_file)
+    laz_base = _strip_lidar_ext(laz_file)
 
     output_las = temp_dir / f"{laz_base}_ground_{method_label}.las"