Server sync conflicts are still silent in client; add explicit pull/push conflict resolution flow #384

Server hash checks are in place, but client sync conflict handling is still weak/silent (notably pull hash-check failures). Users don’t get a clear recovery path when local and remote diverge.

Need to:

remove silent conflict paths
show one conflict modal with clear actions: pull remote, force push local, open remote in new tab, cancel
include context (local hash vs remote hash / remote newer history)
make sync toasts/errors consistent and actionable
keep post-sync status flags coherent

Success when conflicts are always visible, recoverable, and user-driven.