Fix PermissionError deleting locked HDF5 cache on Windows

When the hdf5 serializer constructor fails on an existing
file, the HDF5 C library retains the file handle on Windows.
Force gc.collect() before os.remove() to release it, and
catch PermissionError to skip the cache gracefully if the
file is still locked.

Generated with the assistance of an AI coding tool.

src/bonsai/bonsai/bim/ifc.py

@@ -18,6 +18,7 @@
 
 from __future__ import annotations
 
+import gc
 import hashlib
 import os
 import shutil
@@ -170,7 +171,13 @@ class IfcStore:
                     # No point to trying again the same operation.
                     return
 
-                os.remove(IfcStore.cache_path)
+                # Force GC to release any dangling HDF5 C-level file handle (Windows).
+                gc.collect()
+                try:
+                    os.remove(IfcStore.cache_path)
+                except PermissionError as e:
+                    print(f"Could not delete locked cache file '{cache_path.name}': {str(e)}. Skipping cache.")
+                    return
                 try:
                     IfcStore.cache = ifcopenshell.geom.serializers.hdf5(
                         IfcStore.cache_path, cache_settings, serializer_settings

src/bonsai/bonsai/tool/raycast.py

@@ -25,6 +25,7 @@ import bmesh
 import bpy
 import mathutils
 import numpy as np
+from bpy_extras import view3d_utils
 from mathutils import Vector
 
 import bonsai.core.tool