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>

overrides/5.0/mathutils.json

@@ -0,0 +1,12 @@
+{
+  "Matrix.Translation": {
+    "params": {
+      "vector": "Vector | Sequence[float]"
+    }
+  },
+  "Matrix.Scale": {
+    "params": {
+      "axis": "Vector | Sequence[float]"
+    }
+  }
+}