Might I suggest you give a chance to having separate TODO and WISHLIST and TASKS text files in the root folder that use whatever id scheme you like and point to the code, with the code referring back to those ids only rarely? Or even a single file with sections for those things and more, perhaps called PLAN? Keeping things separate keeps the code tidier, gives you license to put more details than you're likely to put in a one or two line comment, lets you refer to multiple code points instead of the local comment area, can be given to a high school student temp worker, and so forth.

For personal projects I've used https://github.com/dspinellis/git-issue a few times for a local command line issue tracker, it's not bad. I've got a longstanding mental TODO to try out Fossil one of these days though with all that and more integrated...