Show enum members in Annotated types like Literal does

[gyanu2507]

Annotated[int, Color.red] was going through repr(), so autodoc printed <Color.red: 'red'>. Literal already formats enum members as :py:attr: links — reused that for Annotated metadata.

Fixes #14653

[gyanu2507]

The red CI here isn't from this change — it's Pygments 2.21.0, which stopped escaping " as " in its HTML output.

Six tests fail, all of them string-comparing highlighted HTML:

• test_highlighting.py::test_default_highlight
• test_builders/test_build_html_code.py::test_html_code_role
• test_extensions/test_ext_viewcode.py::test_viewcode
• test_extensions/test_ext_viewcode.py::test_viewcode_linenos
• test_intl/test_intl.py::test_additional_targets_should_be_translated
• test_intl/test_intl.py::test_additional_targets_should_not_be_translated

None of them touch sphinx/util/typing.py. To confirm, I checked out this PR's branch point (e44a40e, unmodified master) with Pygments 2.21.0 pinned and got the identical six failures; pinning back to 2.19.2 makes both the branch point and this branch fully green. e44a40e's own CI run was green because it predates the 2.21.0 release on 2026-08-17.

Happy to send the escaping updates as a separate PR if that's useful, or rebase this one once that's sorted — just say which you'd prefer.

[gyanu2507]

Pushed an empty commit to re-run CI on current master.

The earlier red jobs were highlighting tests that assert HTML containing " (e.g. test_html_code_role, test_viewcode, test_default_highlight). That tracks Pygments output escaping, not the Annotated-enum formatting change in this PR. If tip is still red the same way, it is a base-branch / dependency issue rather than this diff.