Prevent stack overflow in BST deletion

[krotname]

Motivation

• The public Solution.remove(Node,int) implementation used unbounded recursion proportional to tree height, which can trigger StackOverflowError on deeply skewed (attacker-controlled) trees and cause availability failures.
• The goal is to eliminate the recursive stack growth while preserving existing deletion semantics (leaf, one-child, two-child using predecessor) and tests.

Description

• Replace recursive lookup-and-delete with an iterative search using parent and current pointers to avoid per-level Java stack frames during traversal.
• Handle nodes with two children by locating and detaching the predecessor iteratively (no recursive call) and copying its value to the deleted node, preserving predecessor-based behavior.
• Remove the recursive findMax/recursive-delete path and return/update child links iteratively; overall auxiliary space becomes O(1).
• Add a regression test removeHandlesDeepSkewedTreeWithoutOverflowingStack that constructs a 100,000-node right-skewed tree and deletes the deepest node to verify no stack overflow and correct tree shape.

Testing

• Ran mvn -Dtest=algorithms.sprint5.SolutionTest test, and the module-specific tests passed (5 tests, all successful).
• Ran full test suite with mvn test, and all automated tests passed (598 tests, all successful).

---

Codex Task

[krotname]

Superseded by the validated combined merge in #115: #115