状态修复缺少非破坏性出口：基线快照缺失时 resync/repair-state/delete 全部拒绝，且报错不指路（附可用绕过途径）

$ inkos write repair-state 南渡北辰 14
Chapter 14 is not state-degraded.

$ inkos chapter delete 南渡北辰 --chapter 15
Cannot delete chapter 15: the state snapshot for chapter 14 is missing
(story/snapshots/14/current_state.md). Nothing was changed.

$ inkos chapter delete 南渡北辰 --chapter 14
Only the latest chapter (15) can be deleted, but chapter 14 was requested.

// :1882-1885  resync：必须是最新章
const latestChapter = Math.max(...index.map((chapter) => chapter.number));
if (targetChapter !== latestChapter) {
    throw new Error(`Only the latest persisted chapter can be synced safely (latest is ${latestChapter}).`);
}

// :1891-1897  resync 还要求基线快照 N−1 —— 所以连最新的 15 也救不了
const baselineChapter = targetChapter - 1;
const baselineStoryDir = join(bookDir, "story", "snapshots", String(baselineChapter));
const [oldState, oldHooks] = await Promise.all([...]).catch((error) => {
    throw new Error(`Cannot sync chapter ${targetChapter} safely: baseline snapshot ${baselineChapter} is unavailable (${String(error)})`);
});

// :1777-1783  repair-state：status 必须为 state-degraded 且必须是最新章
if (targetMeta.status !== "state-degraded") {
    throw new Error(`Chapter ${targetChapter} is not state-degraded.`);
}
if (targetChapter !== latestChapter) {
    throw new Error(`Only the latest state-degraded chapter can be repaired safely (latest is ${latestChapter}).`);
}

// :18-23  中章禁令
// :25-37  回滚目标快照必须可用，否则"Nothing was changed"
const rollbackTarget = latest - 1;
for (const required of ["current_state.md", "pending_hooks.md"]) {
    const snapshotFile = join(bookDir, "story", "snapshots", String(rollbackTarget), required);
    try { await stat(snapshotFile); }
    catch {
        throw new Error(`Cannot delete chapter ${latest}: the state snapshot for chapter ${rollbackTarget} is missing `
            + `(story/snapshots/${rollbackTarget}/${required}). Nothing was changed.`);
    }
}

Cannot delete chapter 15: the state snapshot for chapter 14 is missing (…). Nothing was changed.
Hint: you can rebuild state from an earlier snapshot with `inkos write rewrite <book> 14`
      (this removes chapter 14 and all later chapters), or replay with
      `inkos import chapters <book> --resume-from 14 --from <dir>`.