fix(utils): prevent falsy value cache bypass in ShortCache

[MeiSiristhebest]

Fixes #1160

Motivation

In createShortCache, truthiness evaluation if (cache) causes valid falsy cached values (false, 0, "", null) to be bypassed on every subsequent call, repeatedly re-executing the computation function.

Changes

• Add explicit hasCache: boolean flag to correctly preserve falsy cached primitives.
• Expose clear() and dispose() on ShortCache<T> for deterministic timer cleanup and resource teardown.

Verification

• Added unit test cases covering false, 0, "", and null caching behavior.
• Verified 20 consecutive stress test loops and timeout sliding TTL reset.