* feat(keys): add --keys flag to dump for cross-host decryption
Consumer side of the cross-host key workflow (pairs with #599).
ApplyDump wires StaticProviders from a dump.json into matching
browsers, so dump --keys f.json -p /copied/data decrypts without
native retrievers.
* fix(keys): guard --keys against misuse + hint Safari
Without -p, dumped keys would be applied to local profile data and
decrypt to garbage; -b all hits the same path because pickFromConfigs
ignores -p when name == "all". Require both.
* chore(keys): address PR #600 Copilot review
- example: add -b chrome (without it, --keys + default -b all errors out)
- use %q for keysPath in error wrap, matching surrounding style
Roger