Fix sorting bug in directories comparison

The original comparison function had an issue where it would
return true immediately when a_str was longer than b_str, without
checking the actual string comparison. This led to me getting
consistent build failures. The fix properly compares lengths first,
then falls back to lexicographic comparison only when lengths are
equal.

Author: mtdowling

build/cyan/commands/build.lua

@@ -287,8 +287,10 @@ local function build(args: command.Args, loaded_config: config.Config, context:
       table.sort(unexpected_directories, function(a: lexical_path.Path, b: lexical_path.Path): boolean
          local a_str <const> = a:to_string()
          local b_str <const> = b:to_string()
-         if #a_str > #b_str then
-            return true
+         local a_len <const> = #a_str
+         local b_len <const> = #b_str
+         if a_len ~= b_len then
+            return a_len > b_len
          end
          return a_str > b_str
       end)