fix(deploy): the GRUB fallback's mode checked as git keeps it

The test read the working tree's mode, which follows the umask of
whoever checked it out. CI's runner checks out under 0077, so the
script stood there as 0700 and the test, asking for every execute
bit, failed though git keeps it as 100755. It now asks git, which is
what the host checks out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

test/deploy/halkyon_li_forward_test.dart

@@ -292,9 +292,20 @@ void main() {
           contains(r'[ -e "/boot/vmlinuz-$version" ] || continue'),
         );
         expect(fallback, contains(r'initrd /initrd.img-$version.dracut'));
+        // As git keeps it, which is what the host checks out: the working
+        // tree's mode follows the umask of whoever checked it out, and CI's
+        // runner checks out under 0077.
+        final mode =
+            Process.runSync('git', [
+                  'ls-files',
+                  '--stage',
+                  '--',
+                  'deploy/host/grub-dracut-fallback',
+                ]).stdout
+                as String;
         expect(
-          File('deploy/host/grub-dracut-fallback').statSync().mode & 0x49,
+          mode,
-          0x49,
+          startsWith('100755 '),
           reason: 'executable, as update-grub runs it',
         );
       });