P0-7: the Project Editor's header-section exposed a 'Profile'
toggle (HeaderConfig.showProfile) with no corresponding UI anywhere
in the storefront header — confirmed dead per docs/KNOWN-ISSUES.md
item 5. Toggling it implied a feature (an account/profile menu)
that doesn't exist, which is misleading in the editor.
Building the actual account/profile surface is real feature work
(out of scope for this polish pass), so removed the toggle from the
editor's items list and the field-schema registry instead of
building UI a merchant would flip with no visible effect. The
underlying HeaderConfig.showProfile field and its false default are
unchanged (data model untouched, still available if a future
account feature wires it up).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>