Add self-service API tokens (PATs) with UI + Bearer auth (#35)

Personal access tokens so scripts/CI can call the management API without a
browser session. Each logged-in user mints their own token; it authenticates as
the creator (carries their LDAP group permissions, re-resolved live), so the
existing permission.byGroup checks apply unchanged.

- models/api_token.js: new ApiToken model (sso_<id>_<secret> format; id is the
  lookup key, secret bcrypt-hashed + isPrivate, shown once). add()/rotate()/
  authenticate(); optional expires_at; best-effort last_used_on. No _ttl
  (persists; lifetime via expires_at).
- routes/api_token.js: self-service CRUD (list/get/update/delete/rotate),
  owner-scoped (created_by === req.user.uid, 403 otherwise).
- middleware/auth.js + models/auth.js: accept `Authorization: Bearer sso_...`
  (precedence over the auth-token session header); checkApiToken collapses
  every failure to one generic 401 (no existence/secret/expiry leak).
- views/api_tokens.ejs + routes/index.js (GET /api-tokens): self-service page
  (forceLogin, no group gate) — create (token shown once), edit, rotate, revoke.
- views/top.ejs: "API Tokens" nav entry visible to all logged-in users.
- public/js/app.js: app.apiToken client module.
- DEPLOYMENT.md + docs/deployment.md: API tokens section.

Co-authored-by: Claude <noreply@anthropic.com>

nodejs/views/top.ejs

@@ -46,6 +46,12 @@
   	          Profile
   	        </a>
   	      </li>
+  	      <li class="nav-item">
+  	        <a class="nav-link" href="/api-tokens">
+  	          <i class="fa-solid fa-code"></i>
+  	          API Tokens
+  	        </a>
+  	      </li>
   	      <li class="nav-item group-required group-required-app_sso_admin">
   	        <a class="nav-link" href="/users"><i class="fa-solid fa-users"></i>
   	          Users