Add longnail merge and schedule

toolflow/src/main/scala/com/minres/tgc/hammer/FileUtils.scala

@@ -0,0 +1,11 @@
+package com.minres.tgc.hammer
+
+import os.*
+
+object FileUtils {
+  def changeExtension(path: os.Path, newExt: String): os.Path = {
+    val baseName = path.baseName
+    val newName = s"$baseName.$newExt"
+    path / os.up / newName
+  }
+}