Concurrent, lock-free, no-std stack implementation in Rust.

• Uses atomic compare-and-exchange operations for thread safety
• Implements tagged pointers to prevent the ABA problem
• Each modification increments a tag counter to detect concurrent modifications
• Safe for concurrent access from multiple threads

Example

use unstacked::Stack;
let stack: Stack<i32> = Stack::new();
stack.push(1);
assert_eq!(stack.pop(), Some(1));
assert_eq!(stack.pop(), None);

stack.push(2);
assert_eq!(stack.peek(), Some(2).as_ref());
assert!(!stack.is_empty())