Reuse the attendee contact-picker mechanism for the location field: a
Contacts button beside the location input opens the system picker scoped
to postal-address rows, and the chosen contact's formatted address is
dropped into the field (multi-line addresses collapsed to one line).
Same no-permission guarantee as the guest picker — ACTION_PICK grants
temporary read access, so no READ_CONTACTS is required.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
