fix(model): disable PostgreSQL prepared statements for pooler compatibility

GORM v1.25.2 closes cached prepared statements asynchronously on any SQL
error and immediately re-Parses the same deterministic name (pgx's
stmt_<sha256>) on the same client connection. Transaction-pooling proxies
(PgBouncer >=1.21 with max_prepared_statements, Neon, Supabase) respond
with FATAL "prepared statement name is already in use" (SQLSTATE 08P01)
and drop the connection. PreferSimpleProtocol only disables pgx's
implicit prepare and never covered GORM's explicit PrepareStmt cache.

- PostgreSQL now runs with PrepareStmt disabled entirely; named prepared
  statements are fundamentally session state and cannot be made safe
  under transaction pooling. Parse/plan cost is noise for this workload.
- Upgrade gorm to v1.25.12 so MySQL/SQLite statement caches (still
  enabled) no longer churn close/re-prepare on ordinary SQL errors;
  v1.25.9+ restricts eviction to driver.ErrBadConn. Deliberately not
  v1.26+, whose LRU eviction has an open use-after-close race (#7831).
- sanitizeDBError now attaches a remediation hint on 08P01/42P05 so
  affected deployments can self-diagnose from the log line.

model/main.go

@@ -138,10 +138,12 @@ func chooseDB(envName string, isLog bool) (*gorm.DB, common.DatabaseType, error)
 		if strings.HasPrefix(dsn, "postgres://") || strings.HasPrefix(dsn, "postgresql://") {
 			// Use PostgreSQL
 			common.SysLog("using PostgreSQL as database")
+			// 同时关闭 pgx 隐式与 GORM 显式预处理语句:命名 prepared statement 与
+			// 事务池代理(PgBouncer/Neon/Supabase)不兼容,会触发 FATAL 08P01/42P05。
 			db, err := gorm.Open(postgres.New(postgres.Config{
 				DSN:                  dsn,
-				PreferSimpleProtocol: true, // disables implicit prepared statement usage
-			}), newGormConfig(true))
+				PreferSimpleProtocol: true,
+			}), newGormConfig(false))
 			return db, common.DatabaseTypePostgreSQL, err
 		}
 		if strings.HasPrefix(dsn, "local") {