Audit and remove magic numbers (all projects)

Our incoming new lint does detect `magic-numbers`, and most have just been disabled for compatibility.

Task

- [x] Come up with archetype config base rule, e.g. `no-magic-numbers: ["error", { "ignore": [-1, 0, 0.5, 1, 2] }]` or something.
- [ ] Grep on `no-magic-numbers` in all projects and audit usage / abstract to constants where sensible.
- [x] Search on string `// TODO: magic numbers`