C-01: ConnectionRequestCard now uses local isResponding state instead of
shared hook boolean, so accepting one card doesn't disable all others.
C-03: detach_umbral_contact no longer wipes person data (name, email,
phone, etc.) when a connection is severed. The person becomes a standard
contact with all data preserved, preventing data loss for pre-existing
contacts that were linked to connections.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>