fix: crypto TS类型修复 + EXPLAIN AST类型补充

src/query/ast.ts

@@ -14,6 +14,7 @@ import type { WhereCondition, OrderBy } from '../constants';
 
 export type StatementType =
   | 'SELECT'
+  | 'EXPLAIN'
   | 'INSERT'
   | 'UPDATE'
   | 'DELETE'
@@ -109,6 +110,12 @@ export interface DropTableStatement {
   ifExists?: boolean;
 }
 
+/** EXPLAIN 查询计划 */
+export interface ExplainStatement {
+  type: 'EXPLAIN';
+  query: Statement;
+}
+
 // ---------------------------------------------------------------------------
 //  DML: INSERT
 // ---------------------------------------------------------------------------
@@ -170,6 +177,7 @@ export interface SelectStatement {
 
 export type Statement =
   | SelectStatement
+  | ExplainStatement
   | InsertStatement
   | UpdateStatement
   | DeleteStatement