feat(research): add project list presentation model

[hubab1]

Summary

• add a closure-injected, @MainActor observable project-list presentation model
• preserve prior rows across reload and pagination failures with exact continuation offsets and ID deduplication
• add stable project/keyword draft UUIDs for idempotent persistence retries
• map store, provider, and Apple Ads issues to fixed redacted user-facing messages and truthful accessibility descriptions

Correctness

• stale or cancelled loads cannot overwrite a newer publication
• mutations check cancellation before persistence but never report cancellation after a successful commit return
• a mutation before the initial page, or one that supersedes an in-flight load, exposes requiresReload and blocks unsafe continuation paging until recovery succeeds
• project revisions advanced by detail mutations can be reconciled without accepting older or same-ID reincarnated snapshots
• canceled dependencies that surface a non-cancellation error restore the prior load state
• stale destructive mutations surface a conflict and are never retried automatically
• creating and deleting rows preserve or adjust valid pagination offsets instead of hiding later pages

Validation

• 10 focused presentation-model tests passed
• 427 tests pass at this stack boundary; 445 passed at the current stacked UI head
• signed Debug build passed
• strict deep code-sign verification passed
• independent review findings were fixed and the final P1/P2 review was clear
• GitHub Actions is green for the amended head

Review gate

This is a stacked draft on PR #51 / 34a-research-project-ui-foundation. It is a presentation-only foundation with no UI entry point, provider call, or live-store launch. The inherited V5 persistence stack remains manually gated.

Implementation is independent; no external co-author applies.