Security patch release for the 4.x line.

• getToken() now returns null instead of throwing when the Authorization header contains a malformed Bearer value.
• OAuth state, nonce, and PKCE check cookies are now bound to the provider that created them and are rejected when a different provider handles the callback. Sign-ins in flight across the upgrade fail once and succeed on retry.
• Email addresses are Unicode-normalized (NFKC) before validation in the email sign-in flow, closing a homoglyph @ bypass.
• An explicitly configured NEXTAUTH_URL now takes precedence over the auto-detected forwarded host in trusted-host mode.
• Restores CommonJS compatibility by pinning uuid to ^11.1.1; the 14.x line is ESM-only and broke require() on Node versions below 20.19.