feat(db,contracts): W5-C subscription units migration 0025, contracts and mapping

- subscription: status pending (TMDB not ready: searchable/evaluable, not completable),
  last_searched_at / next_search_at
- content_unit (season): episode_total ledger with source / lock / timestamp
- acquisition_plan: unit_keys (Slot × unit reservation) and file_selection; drop the
  one-in-flight-per-slot unique index (checked under slot row lock per unit instead)
- new tables slot_deferral, slot_unit (per-unit quality ledger), subscription_history
- contracts: SubscriptionParams, SubscriptionHistory, SlotDeferral, SlotUnit, SubscriptionProgress,
  EpisodeTotalSet, CandidateEvaluation pri/trace/unitKeys and decision deferred;
  endpoints subscriptions.search/progress/setEpisodeTotal and subscription-history
- mapping: evaluation messages via describeViolation, pri/trace passthrough

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/contracts/test/db-sync.test.ts

@@ -95,6 +95,10 @@ const ROWS: Record<string, { row: Obj; dbOnly?: string[]; apiOnly?: string[] }>
   BrowserControlLease: { row: C.BrowserControlLease },
   // W5-A 文件管理回收站(0024)
   TrashItem: { row: C.TrashItemRow },
+  // W5-C 订阅增强(0025)
+  SlotDeferral: { row: C.SlotDeferral },
+  SlotUnit: { row: C.SlotUnit },
+  SubscriptionHistory: { row: C.SubscriptionHistory },
 };
 
 /** 引擎自有表(@umt/tasks 内部使用,不经 API 暴露),不要求 Row schema */
@@ -223,6 +227,8 @@ const ENUMS: Record<string, z.ZodEnum> = {
   BrowserTabStatus: C.BrowserTabStatus,
   BrowserControlLeaseHolderKind: C.BrowserLeaseHolderKind,
   BrowserControlLeaseStatus: C.BrowserLeaseStatus,
+  // W5-C(0025)
+  ContentUnitEpisodeTotalSource: C.EpisodeTotalSource,
 };
 
 describe("contracts ⇔ db 表结构同步", () => {