feat: configurable LDAPS hostname (ldapsHost/ldapsPort) and extensive docs (#89)

Add conf.ldap.ldapsHost / conf.ldap.ldapsPort so the /integrations page
can advertise an internal-only LDAPS hostname separate from the public
OAuth issuer. This avoids forcing admins to port-forward 636 publicly.

- routes/index.js derives LDAPS URL from ldapsHost/ldapsPort with issuer fallback
- integrations.ejs adds a contextual help panel explaining TLS hostname
  validation, the public-issuer default, and recommended internal-DNS /
  Docker-internal alternatives
- conf/base.js, secrets.js.example, DEPLOYMENT.md, docs/configuration.md,
  and docs/ldap.md document and expose the new options
- Add tests/integrations.test.js for default and custom ldapsHost behavior
- Bump version to 1.1.17

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

nodejs/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "t42-sso-manager",
-  "version": "1.1.16",
+  "version": "1.1.17",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "t42-sso-manager",
-      "version": "1.1.16",
+      "version": "1.1.17",
       "license": "MIT",
       "dependencies": {
         "@fortawesome/fontawesome-free": "^7.3.0",