Adds `warden access <need> [--domain X] [--json]`: resolves a credential
need against the routing catalog and renders the structured handoff
(owner, auth method, path template, command skeleton, policy gate
status, proxy hint). SSH lane points at `warden sign`; routed lanes end
"warden advises, the owner vends". New pure warden/access.py module
(expand_handoff, policy_gate_status) reused by the T3 proxy lane. JSON
output is stable and secret-free. tests/test_access.py added.
157 passed, lint clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
