context: scope.md public-page entries still describe profiles as opt-in

tsk-qzrjwx56t9nd open

Since the maintainer's decision of 2026-11-02 (§2.7; migration 20261102110000_profiles_public), a person's profile is public by default. context/scope.md still says otherwise:

around lines 616–635, the public pages entry says a person gets a page by turning public_profile on, and that being public is "off until chosen";
around line 700, the Reason of the next entry says "Names follow each person's own choice".

Bring the body up to the current state and keep the history; only the alternatives paragraph records the overturn today. Found by pmwg in the #1351 review (69698), and noted as a P3 on tsk-bxyhjqfsqxf3. It gets its own context PR, after docs page 2.