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/db/migrations/0073_downloader_visibility.ts

@@ -0,0 +1,40 @@
+import type { Kysely } from "kysely";
+import { execDdl, oneOf } from "../src/migration-helpers.ts";
+
+// 下载侧可见性:decision.kind 增加
+// - downloader_offline:下载器连续不可达超过一段时间(按实例去重,恢复后自动关闭)
+// - cache_volume_unknown:下载目录读不到容量(路径映射 / 挂载问题,按卷去重,恢复后自动关闭)
+
+const OLD_DECISION_KINDS = [
+  "identity_ambiguous",
+  "download_stalled",
+  "download_failed",
+  "path_conflict",
+  "space_insufficient",
+  "approval_required",
+  "metadata_conflict",
+  "source_unreachable",
+  "other",
+  "identity_unresolved",
+  "episode_mapping",
+];
+const NEW_DECISION_KINDS = [...OLD_DECISION_KINDS, "downloader_offline", "cache_volume_unknown"];
+
+const swapDecisionKinds = (values: readonly string[]) => `
+alter table decision drop constraint decision_kind_check;
+alter table decision add constraint decision_kind_check ${oneOf("kind", values)};
+`;
+
+// biome-ignore lint/suspicious/noExplicitAny: 迁移不依赖应用表类型
+export async function up(db: Kysely<any>): Promise<void> {
+  await execDdl(db, swapDecisionKinds(NEW_DECISION_KINDS));
+}
+
+// biome-ignore lint/suspicious/noExplicitAny: 同上
+export async function down(db: Kysely<any>): Promise<void> {
+  await execDdl(
+    db,
+    `update decision set kind = 'other' where kind in ('downloader_offline', 'cache_volume_unknown');
+     ${swapDecisionKinds(OLD_DECISION_KINDS)}`,
+  );
+}