fix: useDeepCompareEffect throws on null-prototype objects

[chatman-media]

Closes #2700.

Problem

useDeepCompareEffect (and useCustomCompareEffect / useBattery via the shared src/misc/isDeepEqual.ts) throws when a dependency is an object created with Object.create(null):

TypeError: a.valueOf is not a function

isDeepEqual simply re-exported fast-deep-equal/react, which takes a valueOf/toString shortcut:

if (a.valueOf  !== Object.prototype.valueOf)  return a.valueOf()  === b.valueOf();
if (a.toString !== Object.prototype.toString) return a.toString() === b.toString();

A null-prototype object has no valueOf, so a.valueOf is undefined; undefined !== Object.prototype.valueOf is true, and the code then calls a.valueOf() and crashes. This is the upstream issue epoberezkin/fast-deep-equal#111, which has been unmaintained for years.

When this happens inside the hook, React renders into an error state (the comparison runs during render, so the effect never re-runs and the component breaks).

Fix

Inline the fast-deep-equal/react comparator into src/misc/isDeepEqual.ts and guard the valueOf/toString shortcuts behind a real-method check (typeof … === "function"), so null-prototype objects fall through to the regular own-keys comparison. The React-specific _owner handling is preserved.

Behaviour is otherwise identical — verified by a 200,000-case fuzz comparing the inlined implementation against fast-deep-equal/react (numbers, strings, booleans, null/undefined/NaN, Date, RegExp, nested arrays/objects, Map, functions): 0 divergences on every input that does not use a null prototype.

The now-unused direct fast-deep-equal dependency is dropped from package.json (it remains in the tree transitively, so the lockfile is unchanged).

Tests

Added a regression test to tests/useDeepCompareEffect.test.ts that renders the hook with a Object.create(null) dependency and asserts the comparison never errors and the effect re-runs only on real change.

• Fails on master: Received: [TypeError: a.valueOf is not a function]
• Passes with this change.
• Full suite green: 76 suites / 493 tests; tsc --noEmit and eslint clean.