List registered runtime adapters from the CLI #128

Description

Expose adapter discovery through the requested edgezero --list-adapters interface or a documented equivalent.

The registry already returns a sorted list of registered adapter names. The CLI command/argument surface does not expose a list-adapters operation.

Steps to reproduce

1. Inspect registered_adapters.
2. Compare the CLI top-level arguments and commands with the requested discovery interface.

Expected behavior

Users can inspect the adapters compiled/registered into their CLI without triggering a build or deployment.

Impact

Users must infer available adapters from errors or source configuration.

Proposed fix

Wire the existing registry enumeration into a minimal read-only CLI path and document compiled availability versus project configuration.

Done when

• The CLI lists all registered adapters in deterministic order.
• Output clearly means compiled/registered adapters and does not misrepresent project/provider readiness.
• The command succeeds without a project manifest or credentials.
• Help and focused command coverage include the discovery path.

Related

• Parent: Complete CLI and local developer workflows #124.
• Adapter discovery registry
• Top-level CLI arguments