CLSA-2026-1774002757 Fix CVE(s): CVE-2026-25898

SECURITY UPDATE: global buffer overflow read in UIL and XPM encoders. - debian/patches/CVE-2026-25898.patch: clamp negative pixel index values to zero in WriteUILImage, WritePICONImage, and WriteXPMImage before using them as array subscripts into the Cixel table. - CVE-2026-25898...