fix(identity): persist verified auxiliary season mappings and reuse source ids

packages/db/migrations/0095_auxiliary_identity_members.ts

@@ -0,0 +1,24 @@
+import type { Kysely } from "kysely";
+import { execDdl } from "../src/migration-helpers.ts";
+
+// Bangumi/豆瓣按分季建条目，一个 TMDB 作品可关联多个来源 ID；来源 ID 仍全局唯一。
+// 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,
+    `drop index external_identity_entity_accepted_key;
+    create unique index external_identity_entity_accepted_key on external_identity (media_entity_id, provider, entity_type)
+      where status = 'accepted' and media_entity_id is not null and provider not in ('bangumi', 'douban');`,
+  );
+}
+
+// biome-ignore lint/suspicious/noExplicitAny: 同上
+export async function down(db: Kysely<any>): Promise<void> {
+  // 已有多分季映射时唯一索引重建会拒绝回退，不删除或猜测保留哪条身份。
+  await execDdl(
+    db,
+    `drop index external_identity_entity_accepted_key;
+    create unique index external_identity_entity_accepted_key on external_identity (media_entity_id, provider, entity_type)
+      where status = 'accepted' and media_entity_id is not null;`,
+  );
+}