Migrate broker and repair ownership to project identity v3

[TheGreenCedar]

Parent: #1032

Outcome

Move readiness-broker scopes/snapshots and CLI refresh/repair ownership onto the lossless project identity v3 contract from #974.

Acceptance criteria

• Broker scopes, snapshots, operation ids, locks, and GPU runtime binding use ProjectIdentityV3/workspace_id_v3.
• Existing v1/v2 broker state is reused only when its workspace/project provenance maps unambiguously; otherwise it is isolated and rebuilt.
• Local-refresh, ready-repair, and stdio marker path equality reuse codestory_workspace::same_workspace_path instead of duplicate text case-folding.
• Case-distinct Unix roots cannot share ownership; Windows aliases still match the same existing path.
• Non-default-port repository ids remain distinct through broker persistence and status output.
• Add migration, collision, A/B/A, Unix case-sensitive, and Windows alias tests; update docs/changelog.

Refs #913
Refs #899