Add a command to archive a browser's data files into a zip for cross-host keys import #607

Context

The cross-host workflow needs the origin host's browser data copied to the analyst host before keys import. That copy step is currently manual and awkward.

Motivation

• Full User Data is huge (caches), but only a few small files are needed to decrypt.
• On Windows the live SQLite files (Cookies, Login Data) are locked → a naive copy fails.
• Paths contain spaces; profile markers vary (Preferences vs Preferences_02).

Discovery already resolves exactly which files matter per category — the only missing piece is collecting them into a portable archive.

Proposal

A command (e.g. keys archive -b <browser> -o data.zip) that:

• collects only decryption-relevant files (Login Data, Cookies, Web Data, History, … + Local State + Preferences), excluding caches → small zip;
• reads locked files via filemanager.Session (the existing Windows locked-file bypass);
• keeps the relative User Data layout, so the analyst can unzip and keys import -p <unzipped> directly.

Workflow

origin:   keys export -o keys.json    # keys
          keys archive -o data.zip     # data (this feature)
analyst:  unzip data.zip && keys import -i keys.json -b <browser> -p ./data

Related: #605; import-discovery bug #606.