feat(ldap): opt-in skip TLS verification for ldaps (internal CA)

Add a per-tenant "Skip TLS certificate verification" toggle to the LDAP
admin page so admins can connect to an AD whose ldaps:// certificate is
signed by an internal/self-signed CA (Node error: "unable to verify the
first certificate"). When enabled, ldapts is given
tlsOptions.rejectUnauthorized=false; the flag is ignored for plain ldap://
(no TLS). Defaults to full verification.

New Boolean column LdapConfig.tlsRejectUnauthorized (@default(true)) +
migration; wired through DTOs, config service, all Client creations
(test/groups/user-search/import/sync) and the test-connection endpoint. UI
checkbox with an insecure-network warning (de/en). 3 new service specs;
API 218 green, web 131 green, both apps tsc clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/api/prisma/schema.prisma

@@ -69,6 +69,7 @@ model LdapConfig {
   searchFilter    String             @default("(objectClass=person)")
   syncIntervalMin Int                @default(60)
   isActive        Boolean            @default(true)
+  tlsRejectUnauthorized Boolean       @default(true)
   groupFilterDns  String[]           @default([])
   userExcludeList String[]           @default([])
   lastSyncAt      DateTime?