Conflicts: none textual. Follow-up fixes for develop's changes:
- docs/mkdocs/docs/api/ordered_map/index.md: develop's new paragraph
(#5609) was written for api/ordered_map.md; fixed its relative
ordered_json.md link for the page's new location, plus two
pre-existing links from an earlier merge (ordered_json.md,
features/object_order.md)
- tools/api_checker/api_surface.json: regenerated with libclang 18.1.1
on Linux (swap() noexcept now includes json_base_class_t; new
integral-key contains/count/find/value overloads)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>