Bonsai: don't crash querying a freshly linked IFC with cache off

Link IFC with 'Use Cache' unchecked crashed with FileNotFoundError
when no .ifc.cache.blend existed yet (a fresh link). Regression from
35e3d9c42, which refactored the cache-clear guard from
'if not self.use_cache and blend_filepath.exists()' into
should_clear_cache() but dropped the existence check on the
not-use_cache path, so os.remove() ran on a non-existent file.

Check blend_filepath.exists() first in should_clear_cache() so the
remove is never attempted when there is nothing to clear, while
keeping the query-mismatch cache invalidation intact.

Fixes #8350

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/bonsai/bonsai/bim/module/project/operator.py

@@ -1578,10 +1578,13 @@ class LoadLink(bpy.types.Operator, tool.Ifc.Operator):
         json_filepath = self.filepath_.with_suffix(".ifc.cache.json")
 
         def should_clear_cache() -> bool:
-            if not self.use_cache:
-                return True
+            # Nothing to clear if the cache file was never created (e.g. a
+            # fresh link). Check this first so os.remove below is never
+            # called on a non-existent path, regardless of use_cache.
             if not blend_filepath.exists():
                 return False
+            if not self.use_cache:
+                return True
             data = json.loads(json_filepath.read_text())
             # Empty 'query' - model loaded without custom query.
             # Missing 'query' - model was loaded before custom queries were introduced in Bonsai.