Without a leading slash a pattern matches at any depth, so the rules for
the three built binaries also matched directories: "Assembler" ignored
Source/Assembler. The files already in it stayed tracked, which is why
nothing had gone wrong yet, but a new source file added there would have
been silently untracked and left out of a commit.
Found by git refusing to stage a change to Source/Assembler/firstPass.c.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>