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/test/schema.test.ts

@@ -117,6 +117,8 @@ const EXPECTED_TABLES = [
   "webauthn_challenge",
   // C2-A 跨进程站点限流(0041)
   "rate_limit_bucket",
+  // C2-A PG 短期缓存(0042,UNLOGGED)
+  "kv_cache",
 ].sort();
 
 /** 不走 entityTable() 的表:追加型/引擎自有表,没有 uuid id + created_at/updated_at 三件套 */
@@ -143,6 +145,8 @@ const NON_ENTITY_TABLES = [
   "webauthn_challenge",
   // 限流桶:key 主键,只有 updated_at
   "rate_limit_bucket",
+  // 缓存:(region, key) 主键
+  "kv_cache",
 ];
 
 describe.skipIf(skip)("schema migrations (real PG)", () => {