this took way too long 💀

I added debug mode - press F1 and the interpreter steps through your program
line by line. current line gets a < marker, all assigned variables are
shown live on the right side.
Errors are Highlighted Red and the end is highlighted Green.
I am pretty proud of that

I also spent an embarrassing amount of time chasing a bug where deleting a
character would make the line number of the line below disappear. tried
everything like textbackground resets, gotoxy fixes, cursor position saving,
redraw order changes - none of it worked.

turns out I just forgot to reset debugmode back to 0 after leaving debug mode.
This simple Problem stole 1h of by life 💀

I have also updated the README with debug mode docs, config.txt explanation and swapped
the install section for a direct link to the releases page.