Add minimal bytecode VM execution test

lynglib/src/commonTest/kotlin/BytecodeVmTest.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2026 Sergey S. Chernov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.bytecode.BytecodeBuilder
+import net.sergeych.lyng.bytecode.BytecodeConst
+import net.sergeych.lyng.bytecode.BytecodeVm
+import net.sergeych.lyng.bytecode.Opcode
+import net.sergeych.lyng.obj.toInt
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class BytecodeVmTest {
+    @Test
+    fun addsIntConstants() = kotlinx.coroutines.test.runTest {
+        val builder = BytecodeBuilder()
+        val k0 = builder.addConst(BytecodeConst.IntVal(2))
+        val k1 = builder.addConst(BytecodeConst.IntVal(3))
+        builder.emit(Opcode.CONST_INT, k0, 0)
+        builder.emit(Opcode.CONST_INT, k1, 1)
+        builder.emit(Opcode.ADD_INT, 0, 1, 2)
+        builder.emit(Opcode.RET, 2)
+        val fn = builder.build("addInts", localCount = 3)
+        val result = BytecodeVm().execute(fn, Scope(), emptyList())
+        assertEquals(5, result.toInt())
+    }
+}