feat: propagate CFG_LDAPS_HOST through setup and document LDAPS networking (#71)

Pass optional CFG_LDAPS_HOST from setup.env through setup.sh into the
generated ./config/sso-secrets.js as ldap.ldapsHost. This lets operators
advertise an internal-only LDAPS hostname (e.g. ldap.internal.example.com
or sso-manager) on the SSO /integrations page instead of the public
OAuth issuer, avoiding a public 636 port forward.

- setup.env.example: add CFG_LDAPS_HOST
- setup.sh: read/forward CFG_LDAPS_HOST into sso-secrets.js
- config.example/sso-secrets.js.example: document ldapsHost/ldapsPort
- .env.example: add LDAPS_HOST for legacy .env migrations
- docker-compose.yml: comment warning against public 636 forwarding
- README.md: explain CFG_LDAPS_HOST recommendation
- CHANGELOG.md + bump version to 1.1.19

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

config.example/sso-secrets.js.example

@@ -17,6 +17,9 @@ module.exports = {
 		bindPassword: 'CHANGE-ME',             // slapd root + app bind password
 		userBase: 'ou=people,dc=example,dc=com',
 		groupBase: 'ou=groups,dc=example,dc=com',
+		// ldapsHost: 'ldap.internal.example.com', // optional: internal-only hostname
+		// shown on /integrations for direct LDAPS binds. Empty -> derive from issuer.
+		// ldapsPort: 636,
 	},
 	smtp: {                                   // optional; leave host '' to skip
 		host: '', port: 587, secure: false,