Add LDAP-over-HTTPS API, agent secrets/IAM engines, and join key management

See CHANGELOG.md for the full breakdown. Summary:

- POST /api/v1/ldap/{bind,search}: LDAP-over-HTTPS so a client stops
  speaking raw LDAP and instead calls the SSO, which binds/searches its
  own OpenLDAP on the caller's behalf (DESIGN.md §3).
- LDAP byte-pump relay (utils/ldap_tunnel.js): forwards raw LDAP bytes
  from an agent's local socket into OpenLDAP over the existing agent WSS
  channel; the SSO never parses LDAP (DESIGN.md §4).
- POST /api/v1/agent/secrets: node-scoped OpenBao secret fetch for
  agents, enforced to each agent's own secret/data/nodes/<id>/* prefix
  (DESIGN.md §5).
- iam_apply signed command: push node-scoped IAM config (sudo rules, SSH
  keys, access control, revocation) to an agent (DESIGN.md §6).
- Agent capability badges on the Directory Metrics tab, sourced from the
  agent's own discovery frame.
- Join key management: GET /api/agent/join-keys/:id/agents (which hosts
  enrolled through a key) plus a Manage join keys table in the Install
  Agent modal with Revoke/Delete actions, confirmed inline per-row rather
  than a blocking native confirm() or the shared app.messages.confirm()
  banner (which desyncs across concurrent rows -- see CHANGELOG).
- docs/agents.md: capability matrix updated for the three new
  capabilities, a full secrets-engine walkthrough with screenshots
  (bash + Node consuming a rendered secret, plus the direct-API
  alternative), and the join-key reuse/UI/audit questions answered.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

nodejs/routes/api_agent_ops.js

@@ -0,0 +1,53 @@
+'use strict';
+
+// Agent-facing operations (DESIGN.md §5, §6). These are NOT admin-gated: the
+// caller is the agent itself, authenticated by its own token (the same one it
+// presents on its WSS channel). Mounted at /api/v1/agent.
+
+const express = require('express');
+const baoConf = require('@simpleworkjs/bao-conf');
+const { authenticateAgent } = require('../utils/agent_auth');
+
+const router = express.Router();
+
+// POST /secrets — fetch node-scoped OpenBao secrets for the agent's own node.
+//
+//   { paths: ["secret/data/nodes/<agent-id>/db"] }
+//   -> { status: "ok", secrets: { "secret/data/nodes/<agent-id>/db": { key: value } } }
+//
+// The agent may only read under its own node prefix (secret/data/nodes/<id>/*),
+// so a compromised agent cannot reach other nodes' or shared secrets. The SSO
+// fetches with its own OpenBao access (SSO_VAULT_TOKEN); the agent never holds a
+// Vault token.
+router.post('/secrets', async (req, res, next) => {
+	try {
+		const agent = await authenticateAgent(req);
+		if (!agent) return res.status(401).json({ status: 'error', message: 'unauthorized' });
+
+		const { paths } = req.body || {};
+		if (!Array.isArray(paths) || paths.length === 0) {
+			return res.status(400).json({ status: 'error', message: 'paths (array) is required' });
+		}
+
+		const nodeScope = `secret/data/nodes/${agent.id}/`;
+		const secrets = {};
+		for (const p of paths) {
+			if (typeof p !== 'string' || !p.startsWith(nodeScope)) {
+				return res.status(403).json({ status: 'error', message: `path outside node scope: ${p}` });
+			}
+			const r = await baoConf.request('GET', p);
+			if (r.ok) {
+				const body = await r.json().catch(() => ({}));
+				secrets[p] = (body.data && body.data.data) || {};
+			} else {
+				// Missing secret: return an empty object for that path rather than
+				// failing the whole batch; the agent renders what it can.
+				secrets[p] = {};
+			}
+		}
+
+		return res.json({ status: 'ok', secrets });
+	} catch (err) { next(err); }
+});
+
+module.exports = router;