List supported adapters in ts build help #1061

Description

Make ts build --help state the adapter values accepted by its --adapter option. The ts binary delegates build argument parsing to edgezero_cli::args::BuildArgs; changing the help text should use the values accepted by that dependency rather than a separate manually maintained list.

The original request names Fastly, Cloudflare and Axum. Confirm the complete supported set, including whether Spin is accepted by this command, before writing the final text.

Proposed fix

Update the relevant help text in the CLI or its EdgeZero dependency so operators can see the accepted adapters at the point of use. Keep adapter parsing and validation behavior unchanged.

Done when

• ts build --help lists every currently accepted --adapter value and no unsupported value.
• A help-output test guards the list against drift where the argument is defined.
• Existing valid and invalid adapter arguments continue to behave as before.

Affected area

CLI help / EdgeZero CLI dependency.