fix(cublas): strip CR from Packages.gz fields to fix sha256 comparison

Debian Packages.gz uses CRLF line endings; \r in the captured SHA256
field caused string comparison to fail even when hashes were identical.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/builder/build-cublas.sh

@@ -43,10 +43,10 @@ lookup_pkg() {
     pkg="$1"
     ver="$2"
     gzip -dc "${PACKAGES_GZ}" | awk -v pkg="$pkg" -v ver="$ver" '
-        /^Package: / { cur_pkg=$2 }
-        /^Version: / { cur_ver=$2 }
-        /^Filename: / { cur_file=$2 }
-        /^SHA256: / { cur_sha=$2 }
+        /^Package: / { cur_pkg=$2; gsub(/\r/, "", cur_pkg) }
+        /^Version: / { cur_ver=$2; gsub(/\r/, "", cur_ver) }
+        /^Filename: / { cur_file=$2; gsub(/\r/, "", cur_file) }
+        /^SHA256: / { cur_sha=$2; gsub(/\r/, "", cur_sha) }
         /^$/ {
             if (cur_pkg == pkg && cur_ver == ver) {
                 print cur_file " " cur_sha