chore(deploy): tune postgres memory parameters and limit (CACHE-2)

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

docker/compose.env.example

@@ -17,6 +17,14 @@ PGID=10001
 
 # 备份保留份数(0 = 不轮转)
 BACKUP_KEEP=14
+
+# PG 内存(缺省按 4C/8G 给 PG 3G;调整方法见 docs/runbook/storage.md「PG 参数」)
+# PG_MEM_LIMIT=3g
+# PG_SHARED_BUFFERS=2GB
+# PG_EFFECTIVE_CACHE_SIZE=5GB
+# PG_WORK_MEM=32MB
+# PG_MAINTENANCE_WORK_MEM=256MB
+# PG_MAX_WAL_SIZE=2GB
 LOG_LEVEL=info
 # APP_VERSION=v0.1.0
 # 国内网络构建换源(可选):APT_MIRROR=mirrors.ustc.edu.cn