Fix mypy compatibility and add 5.0 conformance tests

- Qualify bare "object" as builtins.object in bpy.types to avoid shadowing
  by Context.object and similar properties
- Use _Sequence alias import to fix mypy "collections.abc.Sequence not defined"
- Filter out variables that clash with submodule re-exports (e.g. bpy.app)
- Add 5.0 conformance tests from Blender 5.0 mathutils documentation

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

conformance/5.0/test_mathutils_vector.py

@@ -0,0 +1,58 @@
+import mathutils
+
+# Zero length vector.
+vec = mathutils.Vector((0.0, 0.0, 1.0))
+
+# Unit length vector.
+vec_a = vec.normalized()
+
+vec_b = mathutils.Vector((0.0, 1.0, 2.0))
+
+vec2d = mathutils.Vector((1.0, 2.0))
+vec3d = mathutils.Vector((1.0, 0.0, 0.0))
+vec4d = vec_a.to_4d()
+
+# Other `mathutils` types.
+quat = mathutils.Quaternion()
+matrix = mathutils.Matrix()
+
+# Comparison operators can be done on Vector classes:
+
+# (In)equality operators == and != test component values, e.g. 1,2,3 != 3,2,1
+vec_a == vec_b
+vec_a != vec_b
+
+# Ordering operators >, >=, > and <= test vector length.
+vec_a > vec_b
+vec_a >= vec_b
+vec_a < vec_b
+vec_a <= vec_b
+
+
+# Math can be performed on Vector classes.
+vec_a + vec_b
+vec_a - vec_b
+vec_a @ vec_b
+vec_a * 10.0
+matrix @ vec_a
+quat @ vec_a
+-vec_a
+
+
+# You can access a vector object like a sequence.
+x = vec_a[0]
+len(vec)
+vec_a[:] = vec_b
+vec_a[:] = 1.0, 2.0, 3.0
+vec2d[:] = vec3d[:2]
+
+
+# Vectors support 'swizzle' operations.
+# See https://en.wikipedia.org/wiki/Swizzling_(computer_graphics)
+vec.xyz = vec.zyx
+vec.xy = vec4d.zw
+vec.xyz = vec4d.wzz
+vec4d.wxyz = vec.yxyx
+
+# Direct buffer access is supported at runtime via C buffer protocol
+# but not expressible in type stubs (requires Python 3.12+ __buffer__).