To gain Veteran Detective, load up the html file in a good editor (regular old Notepad works just fine on Windows 11) and search for the error message you get when you enter an incorrect code (currently this message starts saying "Wrong code").
You'll find an IF statement, currently looking like this:
if (co == null || co == undefined || co.hc() != setup.gc()) {
Then simply apply elementary programming skills to change the "not equal" test to the opposite:
Specifically (for 0.8 at least), change
co.hc() != setup.gc()
to
co.hc() == setup.gc()
(in other words, replace the exclamation point for an equals to sign)
This means that any code EXCEPT the correct one unlocks Veteran Detective.