Contact payment cannot be selected again after returning from Amount #1034

After resolving a contact in Send, returning from Amount to the contact picker and choosing the same or another contact can finish endpoint resolution but fail to navigate. Closing and reopening Send works around it.

Reported four times during iOS #1002 device review. Source inspection confirms the gap on current master and #1003: SendContactSelectView claims a contact payment context, but returning to the picker does not release it. The next selection reaches claimContactPaymentContext, which rejects any existing claim. Send teardown clears the claim, explaining the workaround.

A fix should release only the abandoned selection's context on returning to the picker, preserve an active scan/payment or replacement context, clear obsolete amount state, and keep authorization and duplicate-payment protection. Cover Back followed by same/different contact, failed resolution, cancellation and rapid selection without real payments. Android replaces the active context when its next scan is prepared, so this exact claim guard does not apply there; verify matching behavior when testing.

This is outside #1002's accessibility/layout diff and remains unfixed. Keep its approved changes separate.