pratikrajverma/linklist ? reverse-engineered prompt

Build me a small C++ linked list practice app that demonstrates the common linked list problems in one place.

I want it to handle a basic singly linked list and also include a doubly linked list example. It should let me create a list, insert at the front, at a position, and at the tail, delete from the front, a position, and the tail, print the list, search for a value, and show the length. Please also include the classic interview style helpers like reversing a list, reversing in groups of k, finding the middle for even and odd length lists, merging two sorted lists, merge sort on a linked list, checking for a cycle, creating and breaking a cycle, finding the intersection point of two lists, and bubble sort for a list.

Make it easy to run and test each operation from a simple menu or a set of clear examples. If you need to look up current best practices or standard C++ details, feel free to check online docs.