* feat(restore): cross-platform restore via dump engine rebuild (#606)
Restore previously required the dump's origin OS, overlaying keys onto locally-discovered browsers. It now rebuilds Chromium engines from the dump's vaults (v2 adds engine kind), so copied data or an archive zip decrypts on any OS.
* fix(restore): polish help text, drop dead check, dedup dump kinds
pflag treats backticked words in flag usage as the value placeholder,
so --data-zip rendered as "--data-zip archive" in help output.
* refactor(cli): flatten keys export/import into dumpkeys/restore
The keys noun-group clashed with the flat dump/list verbs; unify on flat verbs and drop the keys parent. Pure rename, no behavior change.
* docs(rfc): add RFC-013 CLI redesign & cross-host restore
The accepted design doc for the flat-verb CLI redesign and cross-platform restore.
Roger