v0.5.3

chore: add .mailmap to canonicalise author identities (#51)

A benchmark/eval harness committed under placeholder local identities
(eval/t/ferry, all with <name>@localhost emails). Map them onto the real
author so git shortlog/blame/log and the contributor graph attribute them
correctly. Display-only — history is not rewritten. The stale local
user.email override has been reset so future commits carry the real identity.