⚡️ perf(export): 重构大结果集导出链路并支持流式写入

- 新增 ExportFileOptions 统一承载导出格式、进度任务和 XLSX sheet 行数上限
- 查询导出改为流式写入文件，避免一次性缓存整批结果导致高内存占用
- 增加值数组快速路径并复用扫描与写入缓冲，减少逐行 map 分配开销
- 为 ClickHouse、自定义驱动、达梦、SQLServer 和 TDengine 补齐 StreamQuery 支持
- 导出时间字符串仅在形似时间时再解析，避免普通文本被误判改写
- 补充 XLSX 分 sheet、流式导出和基准测试覆盖

internal/db/database.go

@@ -76,6 +76,28 @@ type StatementQueryExecer interface {
 	QueryContext(ctx context.Context, query string) ([]map[string]interface{}, []string, error)
 }
 
+// QueryStreamConsumer receives query metadata and rows incrementally.
+// Implementations can stream rows directly to files to avoid buffering entire result sets in memory.
+type QueryStreamConsumer interface {
+	SetColumns(columns []string) error
+	ConsumeRow(row map[string]interface{}) error
+}
+
+// QueryStreamValueConsumer is an optional fast path for stream consumers that
+// can consume normalized row values in column order without requiring a
+// map[string]interface{} allocation per row.
+type QueryStreamValueConsumer interface {
+	SetColumns(columns []string) error
+	ConsumeRowValues(values []interface{}) error
+}
+
+// StreamQueryExecer is an optional interface for drivers or pinned sessions that can
+// stream query rows incrementally instead of materializing []map rows in memory.
+type StreamQueryExecer interface {
+	StreamQuery(query string, consumer QueryStreamConsumer) error
+	StreamQueryContext(ctx context.Context, query string, consumer QueryStreamConsumer) error
+}
+
 // StatementQueryMessageExecer can run queries on a pinned session and return
 // extra server messages/notices alongside rows.
 type StatementQueryMessageExecer interface {
@@ -178,6 +200,22 @@ func (e *sqlConnStatementExecer) Query(query string) ([]map[string]interface{},
 	return e.QueryContext(context.Background(), query)
 }
 
+func (e *sqlConnStatementExecer) StreamQueryContext(ctx context.Context, query string, consumer QueryStreamConsumer) error {
+	if e == nil || e.conn == nil {
+		return fmt.Errorf("连接未打开")
+	}
+	rows, err := e.conn.QueryContext(ctx, query)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	return streamRowsForDialect(rows, e.scanDialect, consumer)
+}
+
+func (e *sqlConnStatementExecer) StreamQuery(query string, consumer QueryStreamConsumer) error {
+	return e.StreamQueryContext(context.Background(), query, consumer)
+}
+
 func (e *sqlConnStatementExecer) QueryMultiContext(ctx context.Context, query string) ([]connection.ResultSetData, error) {
 	if e == nil || e.conn == nil {
 		return nil, fmt.Errorf("连接未打开")
@@ -275,6 +313,23 @@ func (e *sqlConnTransactionExecer) Query(query string) ([]map[string]interface{}
 	return e.QueryContext(context.Background(), query)
 }
 
+func (e *sqlConnTransactionExecer) StreamQueryContext(ctx context.Context, query string, consumer QueryStreamConsumer) error {
+	conn, err := e.activeConn()
+	if err != nil {
+		return err
+	}
+	rows, err := conn.QueryContext(ctx, query)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	return streamRowsForDialect(rows, e.scanDialect, consumer)
+}
+
+func (e *sqlConnTransactionExecer) StreamQuery(query string, consumer QueryStreamConsumer) error {
+	return e.StreamQueryContext(context.Background(), query, consumer)
+}
+
 func (e *sqlConnTransactionExecer) QueryMultiContext(ctx context.Context, query string) ([]connection.ResultSetData, error) {
 	conn, err := e.activeConn()
 	if err != nil {
@@ -401,6 +456,23 @@ func (e *sqlTxStatementExecer) Query(query string) ([]map[string]interface{}, []
 	return e.QueryContext(context.Background(), query)
 }
 
+func (e *sqlTxStatementExecer) StreamQueryContext(ctx context.Context, query string, consumer QueryStreamConsumer) error {
+	tx, err := e.activeTx()
+	if err != nil {
+		return err
+	}
+	rows, err := tx.QueryContext(ctx, query)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	return streamRows(rows, consumer)
+}
+
+func (e *sqlTxStatementExecer) StreamQuery(query string, consumer QueryStreamConsumer) error {
+	return e.StreamQueryContext(context.Background(), query, consumer)
+}
+
 func (e *sqlTxStatementExecer) QueryMultiContext(ctx context.Context, query string) ([]connection.ResultSetData, error) {
 	tx, err := e.activeTx()
 	if err != nil {