Fix: Enforce upper bounds for rxdelay, txdelay, and direct.txdelay

[kizniche]

Fixes #2433 by enforcing upper bounds for rxdelay, txdelay, and direct.txdelay, based on what is written in the CLI docs.

[dreirund]

Maybe increasing the limits can be useful? As There:
https://github.com/user-attachments/files/26126001/Proposal-.MeshCore.factors.in.selecting.rxdelay.txdelay.and.direct.txdelay.pdf (linked at #2053 (comment)) txdelay = 2.5 is also within the range of proposed settings.

Or just the documentation would need correction, whatever suits the intention?

[kizniche]

Perhaps changing the defaults is warranted, but something that should be discussed in the issue, not the PR. This PR is simply aligning the code with the expected behavior (the docs).

[CullenShane]

Denver already recommends values that are higher than these limits: https://denvermc.com/guides/repeater-setup

[dreirund]

Denver already recommends values that are higher than these limits: https://denvermc.com/guides/repeater-setup

So this PR would break existing use cases -- then I would say find the current maximum values and do a PR that aligns the docs with reality ;-).