Add a real logging abstraction to the miner CLI

[JSONbored]

Problem: Every CLI file uses ad hoc console.log/console.error calls — there's no logging dependency or abstraction at all in the package.

Area: AMS / Observability

Proposal: Introduce a minimal, dependency-light logging abstraction (level-aware, consistent formatting) and migrate the CLI's console calls onto it.

Deliverables:

• A shared logger module used consistently across every CLI command.

Acceptance criteria:

• Log level is configurable (e.g. via an env var or flag) and quiet/verbose modes both work.

[linear-code]

JSO-3495