feat(research): add atomic project copy

[hubab1]

Summary

• add exact, paged previews for copying research-project memberships into an existing tracked app
• perform the copy in one atomic background-store write while reusing shared queries and preserving existing tracked state
• reject stale project, target, query, relationship, and partial-destination changes; allow only validated semantic convergence on retries
• wire the copy service through AppServices without deleting projects, synchronizing providers, or synthesizing ranking history

Verification

• focused copy suite: 7 tests passed, including the 500-membership boundary, rollback and retry, cancellation, concurrency, same-timestamp target replacement, and persistent-store reopen
• full regression suite: 463 tests passed across 44 suites
• signed macOS build succeeded
• codesign --verify --deep --strict passed
• two independent P1/P2 reviews were clear

Review notes

• This is a persistence-sensitive draft and should remain manually reviewed before merge.
• No live application launch was performed against the current local store.
• Depends on feat(research): add shared history workspace #59.