Write compared characters as #char literals

The lexer, parser, and formatter compared bytes with character codes
written as numbers (47, 42, 123, 58, ...). `ziran check --lint` found 226
such comparisons; they now read #char "/", #char "*", #char "{",
#char ":" and so on.

The change is textual only: the generated C of every KSS entry is
identical before and after, and `make test` passes with the pinned Ziran.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>