7 tests exercise AddOtOpcUaAuth + MapOtOpcUaAuth end-to-end against an
in-memory ConfigDb + stub ILdapAuthService. Covers /auth/login (204/401/503),
/auth/ping (401/200), /auth/token (200+JWT shape), /auth/logout (204+clear-cookie).
Scope is the auth contract — not the fused Host bootstrap (cluster + role
gating belongs in the Task 58 multi-node harness). HostBuilder + TestServer
is used directly instead of WebApplicationFactory<Program> because the
test project has no Program entry point and Host needs Akka cluster up.
