docs: document standalone mode; bump to 1.4.0

Add README/docs/secrets.js.example coverage for the new
@simpleworkjs/orm-backed standalone mode (no LDAP/SSO), and promote the
CHANGELOG's Unreleased entry to 1.4.0.

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

nodejs/package.json

@@ -1,6 +1,6 @@
 {
   "name": "t42-jump-host",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "SSH jump host for the theta42 stack — LDAP-authenticated, directory-driven host bridging with audit and metrics",
   "author": [
     {