Convert POD documentation to Markdown and migrate to Justfile

- Convert all POD files to Markdown format
- Replace Makefile with justfile for build automation
- Remove deprecated Debian packaging files and related directories
- Update copyright year from 2013 to 2026 in Constants.pm and loadbars
- Remove obsolete docs directory (bugs, wishlist, and generated files)
- Fix sum() function in Utils.pm to handle undef values properly

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/Loadbars/Utils.pm b/lib/Loadbars/Utils.pm
index b4798f0..56b829d 100644
--- a/lib/Loadbars/Utils.pm
+++ b/lib/Loadbars/Utils.pm
@@ -25,7 +25,7 @@ our @EXPORT = qw (
 sub say (@) { print "$_\n" for @_; return undef }
 sub newline () { say ''; return undef }
 sub debugsay (@) { say "Loadbars::DEBUG: $_" for @_; return undef }
-sub sum (@) { my $sum = 0; $sum += $_ for @_; return $sum }
+sub sum (@) { my $sum = 0; $sum += $_ // 0 for @_; return $sum }
 sub null ($)    { defined $_[0] ? $_[0] : 0 }
 sub notnull ($) { $_[0] != 0    ? $_[0] : 1 }
 sub error ($) { die shift, "\n" }