[RaphaelFakhri]

What kind of change does this PR introduce?

Bug fix.

What is the current behavior?

Fixes #308.

When cookieOptions.domain is set, the browser setItem and applyServerStorage emit a host-only clear only for chunks they remove. Chunks they overwrite keep the same names, so after a host-only to .parent.tld migration the old host-only cookies stay until sign-out. Browsers list the older cookie first, and cookie.parse keeps the first value for a name, so the client reads the old session and its refresh fails.

What is the new behavior?

When domain is set, the host-only clear also covers each chunk being written that already exists in the current cookies. The clears come before the sets, so cookie stores keyed by name only (Next.js ResponseCookies) still keep the domain-scoped set. Writes of new cookies and configurations without domain are unchanged.

Additional context

• Updates the expectation of the existing setItem chunk-cleanup test, which now also clears the host-only storage-key.
• Adds tests for the overwritten chunks in setItem and applyServerStorage, for new cookies (no host-only clear), and for a name-keyed store keeping the set.
• In name-keyed server stores the host-only clear for a rewritten name is still overwritten by the set, as before. The browser document.cookie path and stores that emit one Set-Cookie per entry clear the stale copy.