Document LDAPS and certificate validation for LDAP

[blinkerbit]

Source: gitlab-issues-export.md (Issue 10)

Weight: 2

Problem / context

Security review noted LDAP bind without emphasizing LDAPS / trust store configuration in operator docs.

Suggested approach / acceptance criteria

• Add a short Production LDAP section (README or docs/) covering TLS, cert validation, and threat model for password-on-the-wire.
• Cross-link to relevant config keys.

[blinkerbit]

Status update (Jun 2026): \docs/admin-ldap.md\ covers routes/handlers but lacks production TLS guidance (LDAPS, cert validation, threat model). Still needed per acceptance criteria.