Widen mathutils param types, fix getset_descriptor writability, add conformance tests

- Widen bare mathutils type params (Vector, Euler, etc.) to also accept
  Sequence[float], matching Blender's mathutils_array_parse C behavior
- Fix getset_descriptor readonly detection by probing __set__ on the
  descriptor instead of checking fset (which doesn't exist on C descriptors)
- Accept int | slice keys in __getitem__/__setitem__/__delitem__
- Accept Sequence[element_type] values in __setitem__ for slice assignment
- Add mathutils overrides for Matrix.Translation and Matrix.Scale
- Extend apply_overrides to support ClassName.method_name keys
- Add conformance test files from Blender docs examples
- Disable reportUnusedExpression in conformance checks

Remaining known conformance issues:
- draw_handler_add missing from SpaceView3D
- Vector not nominally Sequence[float] (buffer protocol, swizzle setters)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

main.py

@@ -441,6 +441,7 @@ def conformance_check(versions: list[str] | None = None) -> None:
                     "extraPaths": [str(version_dir)],
                     "typeCheckingMode": "strict",
                     "pythonVersion": python_version,
+                    "reportUnusedExpression": False,
                 }
             )
         )