Historical dashboard modes need centralized operational-control gating

Observed while reconciling COR-3969 / theft PR #781 with a newer dashboard implementation on 2026-09-03: a read-only Hidden/history mode should gate operational surfaces at the page/composition boundary, not only disable row buttons. New queue, SLA, assignment, link-copy, and mutation controls had arrived independently; preserving the history contract required hiding queue navigation and passing operational feature flags as false in Hidden mode, while row components still enforced read-only as defense in depth. Source provenance: local merge review of e3-solutions/theft PR #781 at commit 74aa3e27.