feat(runtime): bind continuations to Gitoxide workspace heads

[zhiiw]

Summary

Binds continuation claims to the exact accepted Gitoxide workspace head and proves restart convergence with production-shaped Host crash tests.

Primary invariant: continuation replay resumes from immutable RuntimeEvents and the same accepted workspace head; it never replays a committed Write/Edit side effect.

Owner: continuation claim authority plus managed session owner.
Atomic boundary: durable continuation claim and accepted-head verification.
Failure state: missing, stale, or mismatched workspace evidence parks/fails closed.
Rollback: no provider continuation is admitted until the exact durable boundary is revalidated.

中文说明

本切片把 continuation claim 绑定到精确的 Gitoxide accepted head，并用真实 Host crash/restart 测试证明收敛。恢复只依据 immutable RuntimeEvents 与同一 accepted workspace head，不会重放已经提交的 Write/Edit 副作用。

[zhiiw]

Superseded by the rebuilt delivery stack #40 -> #41 -> #42. This extraction PR remains available as implementation and review history; no validated logic was discarded.

中文说明

该 extraction PR 已由从最新 main 重建的组合交付栈 #40 → #41 → #42 替代。这里仍保留实现与审查历史，已验证逻辑没有被丢弃。