feat(WARDEN-WP-0017): make the access front door discoverable (not SSH-only)

WP-0014 made ops-warden the operator access front door (warden access --fetch/--exec
proxies an exec_capable secret as the caller), but every discovery surface still told
the pre-WP-0014 "SSH certs only, pointer not key" story — so agents like whynot-design
never found the proxy and concluded they had to message ops-warden for a token value.

Messaging/discoverability only; the conduit security model is unchanged (no custody,
no broker).

T1 — CLI: `warden route` table warden column is now three-valued (issue/assist/route);
route + access JSON gain warden_role + exec_capable and a proxy-aware next_action;
`warden access` closing line leads with "ops-warden can fetch this for you as the
caller" for exec_capable lanes (route-only lanes keep "owner vends").

T2 — .claude/rules/credential-routing.md reframed (lead + routing table role column);
SCOPE one-liner + a second capability block for the access front door.

T3 — registered the State Hub capability "Operator access front door (caller-identity
fetch proxy)" (the hub had no ops-warden security capability at all); messaged
whynot-design the corrected `warden access "npm auth token" --fetch/--exec` path.

210 tests pass, lint clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_routing.py

@@ -248,6 +248,7 @@ def test_cli_show_ssh_json_includes_cert_pattern(repo_catalog_env):
     assert result.exit_code == 0
     data = json.loads(result.stdout)
     assert data["warden_executes"] is True
+    assert data["warden_role"] == "issue"
     assert "warden sign" in data["cert_command"]
     assert data["steps"]
 
@@ -256,8 +257,12 @@ def test_cli_show_routed_has_next_action_not_steps(repo_catalog_env):
     result = runner.invoke(app, ["route", "show", "openbao-api-key", "--json"])
     data = json.loads(result.stdout)
     assert data["warden_executes"] is False
+    # exec_capable lane surfaces as an "assist" role so agents see it is proxyable.
+    assert data["warden_role"] == "assist"
+    assert data["exec_capable"] is True
     assert "steps" not in data
     assert "next_action" in data
+    assert "proxy" in data["next_action"]
 
 
 def test_cli_show_unknown_exits_one(repo_catalog_env):