Prevent RecursionMax stack exhaustion

[krotname]

Motivation

• recursionMax(List<Integer>) previously used unbounded recursion and attempted to remove elements from the input List, which can throw UnsupportedOperationException for fixed-size/immutable lists and can cause StackOverflowError on very large lists.
• Apply a minimal, low-risk fix that preserves the method behavior and existing test expectations while eliminating the availability/crash risk.

Description

• Route recursionMax(List<Integer>) through the existing iterative max(List<Integer>) implementation so the method no longer mutates the caller's list or performs unbounded recursion.
• The private recursive helper is no longer used and recursionMax returns the same values as max for null, empty, single-element, and multi-element lists.
• Add a regression test shouldHandleLargeListsWithoutExhaustingTheStack that uses Collections.nCopies(100_000, 42) to verify large caller-controlled lists are handled without stack exhaustion and without mutating the input.

Testing

• Ran mvn -Dtest=other.RecursionMaxTest test and the modified RecursionMax tests passed.
• Ran full mvn verify and the build completed successfully with 598 tests passing and Checkstyle, PMD, JaCoCo, and SpotBugs gates all passing.
• No automated test failures were observed after the change.

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Codex Task

[krotname]

Superseded by the validated combined merge in #115: #115