Merged PR 2317: Auth stabilisation: add reason-coded guards to MyPortal loaders
Adds incremental auth/session hardening across myportal loader paths (loadMyPortalAppealPage, searchresults, addresssearchresults) with explicit guard ordering and reason-coded diagnostics for missing session, missing session identity, missing cookie identity, contact/account lookup failures, and upstream dependency failures. Includes targeted Phase22 loader guard tests and keeps redirect behaviour policy unchanged.
Related work items: #23020
Robert Bond
4fb62a6773