feat(storage): reserve managed workspace mutations at T1

[zhiiw]

Summary

Make managed mutation ownership durable at T1 so concurrent processes cannot admit two mutations for the same workspace instance.

Primary invariant

From managed T1 until a trusted terminal state, one workspace instance has at most one durable mutation owner.

• Owner: SQLite managed-mutation reservation authority
• Atomic boundary: T1 RuntimeEvents and reservation projection in one transaction
• Failure state: competing admission is rejected; incomplete operation remains reserved for recovery
• Rollback: only a trusted terminal bundle releases the reservation; projection is rebuildable

What changed

• extends managed dispatch facts with reservation identity
• atomically commits T1 and the exclusive workspace-instance reservation
• enforces uniqueness across processes through SQLite constraints
• rebuilds reservations from immutable RuntimeEvents
• adds real process-kill and multiprocess competition coverage

Stack position

This is M2.3a, reviewed as the delta from M2.2.

Base: codex/managed-workspace-git-mutation-candidate-m2-2
Next: codex/managed-workspace-mutation-runtime-admission-m2-3b

Validation

Core/storage builds, T1 kill/reopen, two-process admission competition, prepared-T1 restart blocking, rollback, and projection rebuild tests passed.

Draft limitations

• this layer owns reservation only; Runtime settlement is the next PR
• no production Write/Edit consumer yet
• final delivery must be rebuilt from latest upstream/main

中文说明

概要

本层只证明一个不变量：从 managed T1 落盘到可信终态，同一个 workspace instance 最多只能有一个 durable mutation owner。

• Owner： SQLite reservation authority
• 原子边界： T1 RuntimeEvents 与 reservation projection 同事务提交
• 失败状态： 并发入场被拒绝；未收敛操作保留 reservation 等待恢复
• 释放方式： 只有可信 terminal bundle 能释放，投影可从 RuntimeEvents 重建

这是 M2.3a；Runtime 的结算与结果发布留给下一层。

[zhiiw]

Closed as an obsolete extraction/integration slice. The current delivery path is the merged Gitoxide foundation followed by #40 -> #41 -> #42. This PR remains available as design and implementation history.

中文说明

该 PR 属于旧 extraction/integration 栈，现已失去独立合并价值。当前交付路径是已合并的 Gitoxide 基础，然后依次审查 #40 → #41 → #42。这里继续保留设计、实现与审查历史。