Add OIDC login and per-domain authorization

Authentication previously implied full authorization: any valid token
could manage every host, DNS provider, domain, and user. This adds SSO
login and a per-domain rights model.

OIDC login (authorization_code + PKCE):
- conf.oidc + conf.auth blocks; clientSecret in (gitignored) secrets.js.
- utils/oidc.js (state/PKCE, code exchange, userinfo) using global fetch.
- models/oidc_state.js: short-lived state store, auto-expiring via
  model-redis 1.5 per-key TTL.
- routes/auth.js: GET /auth/oidc/start + /auth/oidc/callback; JIT-provisions
  a local user, mints an AuthToken carrying the SSO groups, hands the token to
  the browser via a URL fragment. "Log in with SSO" button on the login page.

Authorization (groups + app overrides, per-domain, with ownership):
- models/grant.js + utils/roles.js (pure, unit-tested): effective rights from
  conf.auth (admin users/groups, group->role map), Grant records
  (user|group -> global|domain -> viewer|manager|admin), and ownership
  (created_by). Roles rank admin > manager(owner) > viewer.
- AuthToken stores session groups; middleware/auth.js exposes req.groups.
- middleware/authz.js: requireAdmin, requireDomainRole(minRole, resolveDomain),
  filterViewable. Applied across routes: host mutations need manager on the
  host's domain; reads are filtered to visible domains; DNS providers, user
  management, and grant management are global-admin-only; certs need viewer.
- routes/grant.js: admin CRUD for grants. Anti-lockout via conf.auth.adminUsers
  plus migrations/grant_bootstrap.js.

Frontend: /me returns effective rights; nav gates Users/Grants to admins;
grants management page; OIDC token-fragment handling in app-base.js.

Tests: utils/roles and utils/oidc unit-tested (no redis); wired into the test
scripts. Full suite 89 pass. Also verified end-to-end against redis (grant
resolution, middleware allow/deny/403, list filtering) and the OIDC pure flow.

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

nodejs/utils/oidc.js

@@ -0,0 +1,125 @@
+'use strict';
+
+const crypto = require('crypto');
+const conf = require('@simpleworkjs/conf');
+
+/**
+ * Minimal OpenID Connect authorization-code + PKCE client.
+ *
+ * The SSO publishes no jwks_uri, so we do not verify ID-token signatures;
+ * instead we treat the flow as opaque and read identity from the userinfo
+ * endpoint (the access token is exchanged server-side over TLS). Uses Node's
+ * global fetch (Node 18+) and crypto — no external dependency.
+ *
+ * All endpoints and client config come from conf.oidc (+ clientSecret from
+ * secrets.js, deep-merged by @simpleworkjs/conf).
+ */
+
+const base64url = buf => buf.toString('base64')
+	.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
+
+// A high-entropy random string for `state` / PKCE verifier.
+function randomToken(bytes = 32){
+	return base64url(crypto.randomBytes(bytes));
+}
+
+// PKCE S256 challenge derived from the verifier.
+function codeChallengeS256(verifier){
+	return base64url(crypto.createHash('sha256').update(verifier).digest());
+}
+
+// Generate the {state, codeVerifier, codeChallenge} triple for a new login.
+function createAuthRequest(){
+	let state = randomToken(32);
+	let codeVerifier = randomToken(32);
+	let codeChallenge = codeChallengeS256(codeVerifier);
+	return {state, codeVerifier, codeChallenge};
+}
+
+// Build the SSO authorize URL the browser is redirected to.
+function buildAuthUrl(state, codeChallenge){
+	let o = conf.oidc;
+	let params = new URLSearchParams({
+		response_type: 'code',
+		client_id: o.clientId,
+		redirect_uri: o.redirectUri,
+		scope: (o.scopes || ['openid', 'profile', 'email', 'groups']).join(' '),
+		state,
+		code_challenge: codeChallenge,
+		code_challenge_method: 'S256',
+	});
+	return `${o.authorizationEndpoint}?${params.toString()}`;
+}
+
+// Exchange an authorization code for tokens at the token endpoint.
+async function exchangeCode(code, codeVerifier){
+	let o = conf.oidc;
+	let body = new URLSearchParams({
+		grant_type: 'authorization_code',
+		code,
+		redirect_uri: o.redirectUri,
+		client_id: o.clientId,
+		client_secret: o.clientSecret,
+		code_verifier: codeVerifier,
+	});
+
+	let res = await fetch(o.tokenEndpoint, {
+		method: 'POST',
+		headers: {
+			'Content-Type': 'application/x-www-form-urlencoded',
+			'Accept': 'application/json',
+		},
+		body: body.toString(),
+	});
+
+	if(!res.ok){
+		let text = await res.text().catch(() => '');
+		let error = new Error('OidcTokenExchangeFailed');
+		error.name = 'OidcTokenExchangeFailed';
+		error.message = `Token exchange failed (${res.status}): ${text}`;
+		error.status = 502;
+		throw error;
+	}
+
+	return res.json();
+}
+
+// Fetch the userinfo claims for an access token.
+async function fetchUserInfo(accessToken){
+	let o = conf.oidc;
+	let res = await fetch(o.userinfoEndpoint, {
+		headers: {
+			'Authorization': `Bearer ${accessToken}`,
+			'Accept': 'application/json',
+		},
+	});
+
+	if(!res.ok){
+		let error = new Error('OidcUserInfoFailed');
+		error.name = 'OidcUserInfoFailed';
+		error.message = `Userinfo request failed (${res.status})`;
+		error.status = 502;
+		throw error;
+	}
+
+	return res.json();
+}
+
+// Pull the app username and group list out of userinfo claims per conf.
+function claimsToIdentity(claims){
+	let o = conf.oidc;
+	let username = claims[o.usernameClaim || 'preferred_username'] || claims.sub;
+	let groups = claims[o.groupsClaim || 'groups'] || [];
+	if(!Array.isArray(groups)) groups = [groups].filter(Boolean);
+	return {username, groups, claims};
+}
+
+module.exports = {
+	randomToken,
+	codeChallengeS256,
+	createAuthRequest,
+	buildAuthUrl,
+	exchangeCode,
+	fetchUserInfo,
+	claimsToIdentity,
+};