Preview contact merges before confirming them

Merging a duplicate lead into a user permanently deletes the lead profile, and until now teammates confirmed that merge without seeing what it would change.

Merge on a potential duplicate in the Inbox now opens a preview showing every attribute side by side, which value survives, and how many conversations, tickets, notes, tags, and phone calls move across. Nothing is written until you confirm, so your team can clear up duplicate contacts with confidence.