Entry: Export ObjectEntry and ObjectEntries types

[derodero24]

Closes #649

Summary

• Export ObjectEntry and ObjectEntries as public types that can be used directly with object types
• These types preserve generic type information that would otherwise be lost when using the conditional Entry/Entries types with generic type parameters
• Add JSDoc documentation with @example and @see cross-references
• Add tests verifying both direct usage and generic type parameter preservation

Context

The Entries<T> type uses conditional type dispatch (T extends Map ? ... : T extends Set ? ... : ...), which causes TypeScript to lose type information when T is a generic type parameter. The internal ObjectEntry/ObjectEntries types don't have this limitation since they work directly with object types without conditional dispatch. Exporting them gives users a way to get properly typed Object.entries() results in generic contexts.

[sindresorhus]

Suggested change

	expectType<['a' | 'b', string | number]>(genericEntry);
	expectType<['a' | 'b', string | number]>(genericEntry);
	// Entry and Entries can widen in generic object contexts because they are conditional over collection kinds.
	type EntryAssignability<BaseType extends Record<string, unknown>, EntryType extends [keyof BaseType, BaseType[keyof BaseType]]> = EntryType;
	// @ts-expect-error -- Entry<BaseType> can widen to the generic constraint when BaseType is generic.
	type EntryAssignabilityTest<BaseType extends Record<string, unknown>> = EntryAssignability<BaseType, Entry<BaseType>>;
	type EntriesAssignability<BaseType extends Record<string, unknown>, EntriesType extends Array<[keyof BaseType, BaseType[keyof BaseType]]>> = EntriesType;
	// @ts-expect-error -- Entries<BaseType> can widen to the generic constraint when BaseType is generic.
	type EntriesAssignabilityTest<BaseType extends Record<string, unknown>> = EntriesAssignability<BaseType, Entries<BaseType>>;

[derodero24]

Applied the suggestion — thanks for pointing out this case. These tests clearly document why ObjectEntry/ObjectEntries are needed as direct alternatives.