feat(cache): PG kv_cache ported from MP TTLCache, TMDB request and recognize caches

Migration 0042_cache adds UNLOGGED kv_cache. PgCache mirrors MP
runtime/cache.py (region, per-key TTL, TLRU maxsize eviction, @cached as
cachedCall); only the storage moves from memory to PG. TMDB request
responses (MP TMDb.request @cached) and recognize results (MP TmdbCache:
same key, {id:0} negative cache with EMPTY_RESULT_CACHE_TTL, type-conflict
checks, backfill after manual assignment) live in kv_cache, shared by all
processes. Settings cache.tmdbTtlHours / tmdbMaxSize / emptyResultTtlSec
map to META_CACHE_EXPIRE / CONF.tmdb / EMPTY_RESULT_CACHE_TTL. TMDB
details now also store posterPath / backdropPath.

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

packages/db/src/index.ts

@@ -1,5 +1,14 @@
 // 统一从本包取 Kysely 与 sql,避免各包各装一份 kysely
 export { type Kysely, sql, type Transaction } from "kysely";
+export {
+  type CachedOptions,
+  cachedCall,
+  DEFAULT_CACHE_SIZE,
+  DEFAULT_CACHE_TTL,
+  PgCache,
+  pgCacheFor,
+  type SetOptions as CacheSetOptions,
+} from "./cache.ts";
 export { type CreateDbOptions, createDb } from "./client.ts";
 export { createMigrator, MIGRATIONS_DIR, type MigratorOptions, migrateToLatest, resetSchema } from "./migrator.ts";
 export {