* Normalize naming for the stack size CI file
* Extend stack size CI with `posh` and `lksh`
`posh` is a derivative of `pdksh` explicitly intended for ensuring
Debian-policy-compliance.
`lksh` is more-POSIX-esque, legacy shell included along-side `mksh`.
* Ensure a signed long overflow won't occur
Also fixes `write_bytes` when the written bytes have alphabetical digits when
encoded as hexadecimal.
* Improve sh semantics in stack-size workflow