CLSA-2026-1779369819 Fix CVE(s): CVE-2026-40686, CVE-2026-40687

SECURITY UPDATE: heap read out-of-bounds in UTF-8 expansion - debian/patches/CVE-2026-40686.patch: harden $fromutf8: expansion operator against malformed UTF-8 trailing bytes. - CVE-2026-40686 SECURITY UPDATE: SPA authenticator buffer hardening - debian/patches/CVE-2026-40687.patch: zero...