Document hard config dependency: absent systemrealm.cfg hangs startup (fail-closed) after activation-order fix

[craigpnnl]

Operational consequence of the primary activation-order fix. After the fix, if pnnl.goss.core.security.systemrealm.cfg is absent, ConfigurationPolicy.REQUIRE means the system realm never publishes, the mandatory @Reference never binds, and startup hangs with no broker. This is strictly safer than the old crash (no insecure broker starts) but is a new operational failure mode. Document the hard config dependency in ops/RELEASING notes so an absent systemrealm.cfg reads as an intentional startup hang, not a bug.

Workspace card: GADP-015. Related: GRIDAPPSD/GOSS-GridAPPS-D#1882.

[craigpnnl]

Resolved by PR #47, merged to develop on 2026-07-10. Closing manually: the auto-close keyword only fires on merges to the default branch (master), and this merged to develop.