feat(cli): show the wallet addresses in inference status

[flyworker]

Part 1 of #134. Part 2 (set-owner) is deliberately untouched — the platform refuses a provider-initiated owner change today, so the command could only ever fail.

What changed

inference status now prints the addresses the platform holds:

Provider Name: Nova Provider
Owner:        not set
Beneficiary:  not set
Status: active

set-beneficiary reads the stored value back instead of echoing the argument. Repeating what was typed confirms nothing — the point of showing it is to see what the platform now holds, on the same terminal. It also warns if the two differ.

No platform change needed: both come from GET /api/v1/provider/me, behind the same provider API key set-beneficiary already uses.

Three decisions worth reviewing

Addresses print in full, not abbreviated. The issue's sketch showed 0x46f2…F93c, but the stated purpose is confirming the value landed on the address you meant — and a truncated form hides the middle, which is exactly where a transposed character sits. Happy to switch to the abbreviated form if the intent was display-only.

The lookup is advisory. It is a second endpoint, so a failure omits the addresses and prints the rest of the status. A diagnostic command should not fail because one extra call did.

--json keeps its existing shape. The addresses are embedded, not nested — every key that was there before stays where it was:

keys: api_key_valid, beneficiary_address, can_connect, earnings_enabled, message,
      name, next_steps, owner_address, provider_id, status, step, step_label,
      total_steps, worker_address

My first attempt nested the status under a status key, which would have broken anything already parsing it. There is a test pinning the flat shape so it cannot regress.

Verified

Run against the live API on a provider whose addresses are all empty, which is the case most likely to render badly — both the human output and --json are correct, and not set reads clearly.

3 tests: the fetch (path and auth header asserted), a non-200 surfacing as an error rather than an empty address set, and the flat JSON contract.

8/8 packages, go vet and gofmt clean. Documented in docs/cli/README.md.