feat(cli): archive a share with gander archive

[scott]

Summary

• Add gander archive to hide a share without deleting it. It resolves a path, short id, or URL the same way gander remove does, including --pick, --all, --yes, and --non-interactive.
• A TTY confirms first. The prompt says the link is hidden, commenting is turned off, and sharing the file again restores the previous visibility and commenting. Declining does not call the server. The local shares map keeps the path.
• After a successful archive, a share watch on that file stops. A directory watch stays up and does not re-adopt the file, so a later save does not unarchive it. A push that gets HTTP 409 archived drops that file the same way.
• gander list prints an ARCHIVED column. Help, shell completion, the man page, and the README mention the command.

The bearer route shipped in gandermd#164. The docs pages are in https://github.com/gandermd/gandermd/pull/165.

Related Issue

Closes #141

Testing

• go test ./... passed
• go vet ./... passed
• go build ./... passed

Notes

--all archives every match of the one required argument. It does not archive every share in the account. A second archive of the same share prints the same success line. gander remove of an archived share still deletes it.