feat(research): add shared history presentation model

[hubab1]

Summary

• add an explicitly @MainActor observable presentation model for paged research history
• preserve shared query-result evidence without inferring an App Store rank for a pre-live project
• reject stale membership generations, merge pages deterministically, and reconcile committed refreshes before continuing offset pagination
• restore truthful load state across cancellation races

This progresses #3 but does not close it.

Validation

• focused history-model tests passed
• full OpenASO suite passed: 578 tests (582 parameterized test invocations)
• project-file lint and whitespace checks passed