lakebox: add ssh-key list/delete, default register --name, fix list null body

[akshaysingla-db]

Three related ssh-key UX changes plus a wire-format bug in list:

1. ssh-key list (new subcommand): GET /api/2.0/lakebox/ssh-keys. Renders the user's registered keys with a * gutter marker on the key matching this machine (using the existing keyHash helper from bd72f85). --json for scripting.

2. ssh-key delete <key-hash> (new subcommand): DELETE /api/2.0/lakebox/ssh-keys/{key_hash}.

3. register --name (new flag): defaults to this machine's hostname when not provided so ssh-key list is meaningful across multiple machines. Previously every locally-registered key landed with an empty name and surfaced as (unset).

4. Fix lakebox list against any workspace that actually has lakebox deployed. Pieter's SDK ApiClient rewrite (08a56be) wrote the pagination call as Do(..., headers, query, nil, &resp) — but the SDK's makeRequestBody treats slot 6 (request) as the GET query string and slot 5 (queryParams) as ignored on GET. Routing the query through slot 5 with a nil body in slot 6 makes the SDK serialize nil as the literal JSON null, sent as the request body on a GET, which the lakebox manager rejects with INVALID_PARAMETER_VALUE: Request body must be a JSON object. Swap the args.

Co-authored-by: Isaac

Changes

Why

Tests

Tested against dbsql-dev-testing-default (workspace with lakebox deployed but no sandboxes):

• lakebox list returns 200 OK with no body, prints "No lakeboxes found." (previously 400'd)
• lakebox ssh-key list renders both keys with correct column alignment; * gutter marks the local key
• lakebox ssh-key list --json round-trips through jq
• lakebox ssh-key delete <hash> — not yet exercised end-to-end
• lakebox register --name laptop against a clean workspace — confirm name lands

[github-actions]

Waiting for approval

Based on git history, these people are best suited to review:

• @pietern -- recent work in cmd/lakebox/
• @shuochen0311 -- recent work in cmd/lakebox/

Eligible reviewers: @andrewnester, @anton-107, @denik, @renaudhartert-db, @shreyas-goenka, @simonfaltum

_{Suggestions based on git history. See OWNERS for ownership rules.}