Add support for agent cloud create and agent cloud claim commands

[const-cloudinary]

Claimable Clouds are temporary clouds whose credentials work immediately, with media delivery restricted to an IP allow-list, disabled after ~24h unless a human claims them.

agent cloud create provisions one and saves it as a named configuration along with the claim URL, which the server returns exactly once and cannot be looked up again. Delivery IPs are forwarded verbatim: the server owns the count, routability and CIDR rules, and rejects bad input with a 400 that does not consume creation quota.

agent cloud claim opens (or prints) the stored claim URL. --print and --json never launch a browser, so headless and agent callers get the URL on stdout.

Config metadata is carried as query params on the saved cloudinary:// URL: claim_url, expires_at, delivery_ips, account_id and cloud_email. config -ls gains a STATUS column and config -s a header flag, both showing an expiry countdown; JSON output carries raw timestamps plus claimable_cloud and expired flags.

Extract parse_expiry, is_expired and expires_in_hint into utils, shared by the OAuth epoch expiry and the ISO-8601 cloud expiry.

Document both commands in the README, and split Requirements into an agent path and a human path so Claimable Clouds are the documented way for an agent to get an account.

Brief Summary of Changes

What does this PR address?

• GitHub issue (Add reference - #XX)
• Refactoring
• New feature
• Bug fix
• Adds more tests

Are tests included?

• Yes
• No

Reviewer, please note:

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I ran the full test suite before pushing the changes and all the tests pass.