CVE-2026-47675: Hono: Cookie helper does not sanitize sameSite and priority, allowing Set-Cookie injection

The serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does not apply the same validation to sameSite and priority. An application that passes user-controlled input into either option may produce a Set-Cookie response header containing attacker-chosen additional attributes.