Surface redirect_uris and is_public in client list/get output

[nycomp]

Fixes #21

What

_format_client() projected only id, name, description, created_at, permissions, so campus client list --json and campus client get --json silently dropped redirect_uris and is_public. Both fields are now projected, and table mode shows them too.

• JSON: adds "redirect_uris": client.redirect_uris or [] (null coerced to []) and "is_public": client.is_public to the projection used by client list/get/new/update --json.
• Table mode: prints a Redirect URIs: block (one URI per line, (none) when empty) and a Public client: yes|no line — indented under each client in client list, appended after Permissions in client get/new/update details. Existing lines are unchanged.

Why

redirect_uri registration is now operational: campus will enforce exact-match redirect_uri validation at /authorize (RFC 6749 §3.1.2.2). An admin surveying "which clients have no redirect_uris registered?" was getting a wrong answer from the CLI and had to fall back to the Python API.

Tests

• Unit: projection includes both fields; null redirect_uris coerces to [].
• Integration: client get/list/update --json payloads expose the fields; table mode renders the URI block and public flag.
• Fixed a latent fixture gotcha: Mock(name=...) names the mock rather than setting the attribute, which broke JSON serialization once client get --json gained a test.
• Suite: 106 passed, ruff clean (hooks run manually against the main checkout's venv — worktree has no .venv).