feat: rebuild web UI on the shared theta42 app stack; OIDC + local admin auth

The web management UI was a bespoke minimal theme with LDAP-bind login.
Rebuild it to match the SSO Manager and Proxy — same stack, same look/feel,
same auth model. The SSH bridge, audit, metrics, and access logic are
unchanged; this is purely the web layer.

Frontend (mirrors proxy/sso):
- Express + EJS with the shared top.ejs/bottom.ejs shell, Bootstrap 5,
  jQuery, jq-repeat, FontAwesome, Socket.IO, and the shared app-base.js /
  val.js client framework (copied verbatim). Vendor libs served from
  node_modules via /static-modules; app assets via /static.
- Dashboard / Sessions / Audit pages render in the common look/feel,
  loading data through the authenticated /api/* endpoints.

Auth (mirrors proxy):
- OIDC against the SSO (utils/oidc.js + routes/auth.js + models/oidc_state)
  plus a local anti-lockout admin (models/user_redis.js, bootstrapped from
  auth.adminUsers[0] / auth.localAdminPass). AuthToken sessions carry the
  group snapshot; middleware gates the data API on adminGroups or the local
  admin. New config: oidc{} + auth.adminUsers/localAdminPass.
- /api/user/me drives the client login state; "Log in with SSO" hidden when
  oidc.enabled is false.

Verified end to end: local admin login -> token -> /api/user/me isAdmin,
metrics/sessions/audit 200 with token / 401 without / 401 bad password;
static + page shells serve; 26 tests green.

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

README.md

@@ -91,9 +91,13 @@ The default SSH port is **2222** so the service needs no privilege. To listen on
 
 ## Web UI / API
 
-`https://jump.example.com/` (behind the proxy) — admin login uses your LDAP
-credentials and requires membership in `auth.adminGroups` (default
-`app_sso_admin`).
+`https://jump.example.com/` (behind the proxy) — built on the same
+Express + EJS + Bootstrap stack as the [SSO Manager](https://theta42.github.io/sso-manager-node/)
+and [Proxy](https://theta42.github.io/proxy/), so it looks and behaves like the
+rest of the stack. Login is **OIDC against the SSO** (the "Log in with SSO"
+button) plus a **local anti-lockout admin** that works even if the SSO is
+unreachable. Admin access requires membership in `auth.adminGroups` (default
+`app_sso_admin`) or being the local `auth.adminUsers` account.
 
 - `GET /health` — open; `{status, activeSessions, version}`
 - `GET /api/sessions` — active sessions