feat: Add PhyslibAlpha to TODO items

[jstoobysmith]

Made using Claude Opus 4.8. Though the changes here are minor.

Adds PhyslibAlpha to the TODO item collection, making sure that they appear in the TODO list.

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[morrison-daniel]

I think it would be good to separate PhyslibAlpha TODOs from the rest. Probably making one category for all of PhyslibAlpha is sufficient since the idea of PhyslibAlpha is to be low impact on maintenance and I foresee fewer TODOs as stuff will be added "as is".

[jstoobysmith]

@morrison-daniel Sounds good, will make this change now.

[zhikaip]

LGTM. but honestly before I looked at this I thought this would be saying upstreaming physlibalpha to physlib as a todo, maybe there should be a mechanism that we should also think about for a process to do so