TODO checker workflow

## Summary

Scan for TODO/FIXME and open/track items.

## CNA mapping

CNA: `todo.yml`.

## Acceptance criteria

- [ ] Workflow present
- [ ] Does not spam duplicates

## Blocked by

_none_

## Blocks

_none_

## Reference

Parity matrix (workspace): knowledge/create-python-app-parity-matrix.md
Reference repo: https://github.com/Create-Node-App/create-node-app


## Parent epic

#7
