feat(db): 待处理新增「下载器连不上」「下载目录读不到容量」两类（迁移 0073）

decision.kind 增加 downloader_offline / cache_volume_unknown,契约、原因文案与界面标签同步;
volume_state_unknown 的原因文案改为「下载目录读不到容量」并指向路径映射与容器挂载。

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Cxwgnn2pbzQ7rXv3rq7fei

packages/contracts/src/reasons.ts

@@ -66,7 +66,7 @@ const REASONS: Record<string, ReasonText> = {
   not_found: { text: "没找到" },
   precondition: { text: "前置条件不满足" },
   internal: { text: "内部错误" },
-  volume_state_unknown: { text: "下载盘用量未知", action: "在下载面板检查下载盘" },
+  volume_state_unknown: { text: "下载目录读不到容量", action: "检查下载器的路径映射和容器挂载" },
   hard_threshold_reached: { text: "下载盘已到暂停线" },
   projected_over_threshold: { text: "下完会超过下载盘暂停线" },
   awaiting_resume_watermark: { text: "等下载盘降到恢复线" },
@@ -85,6 +85,8 @@ const REASONS: Record<string, ReasonText> = {
   download_failed: { text: "下载失败" },
   download_stalled: { text: "下载无进展" },
   space_insufficient: { text: "空间不足" },
+  downloader_offline: { text: "下载器连不上" },
+  cache_volume_unknown: { text: "下载目录读不到容量" },
   unidentifiable: { text: "没识别出作品" },
   user_deleted: { text: "已删除" },
   // DL-3:还没提交就结束或在等的下载(计划的 statusReason、提交任务的延后原因)