fix(send): sync contacts on in-list grant and fix on-Flipcash scroll offset

[bmc08gt]

• Keep the contacts permission gate visible until the full sync completes (via ContactSyncComplete) instead of advancing the moment device contacts land. Advancing early rendered the list before on-Flipcash contacts were fetched, then prepended them above the viewport once they arrived — pushing them offscreen so the user had to scroll up.
• Dispatch ContactsGranted when the user allows access from the in-list rationale card so the contact sync fires, mirroring the gate.
• Hoist ContactAccessHandle out of ContactList; the screen now owns the single handle and wires both Granted (sync) and Picked (add contacts).