🐛 fix(sql-parser): 修复尾随注释导致事务与只读判定异常

- 过滤分号后的纯注释语句并保留数据库可执行版本注释
- 前后端按数据库方言统一处理双横线、井号与块注释
- 修复事务选择、只读保护、SQL 审计及 AI 风险分析误判
- 补充流式 SQL、事务执行与方言解析回归测试

internal/app/sql_split_stream_test.go

@@ -0,0 +1,41 @@
+package app
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestStreamSQLFileDropsCommentOnlyTail(t *testing.T) {
+	t.Parallel()
+
+	var statements []string
+	count, err := streamSQLFile(
+		strings.NewReader("DELETE FROM users WHERE id = 1; -- keep this operation pending"),
+		func(_ int, statement string) error {
+			statements = append(statements, statement)
+			return nil
+		},
+	)
+	if err != nil {
+		t.Fatalf("streamSQLFile returned error: %v", err)
+	}
+	if count != 1 {
+		t.Fatalf("expected one executable statement, got %d", count)
+	}
+	want := []string{"DELETE FROM users WHERE id = 1"}
+	if !reflect.DeepEqual(statements, want) {
+		t.Fatalf("expected statements %#v, got %#v", want, statements)
+	}
+}
+
+func TestSQLStreamSplitterPreservesExecutableMySQLComment(t *testing.T) {
+	t.Parallel()
+
+	splitter := &sqlStreamSplitter{}
+	got := splitter.Feed([]byte("/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;"))
+	want := []string{"/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("expected statements %#v, got %#v", want, got)
+	}
+}