BIP 440/441: document varops budget edge cases and other clarifications #2231

Updates BIP 440 and BIP 441:

1. document mixed-version resource limits, including the potential 2× validation cost of adversarial input mixing
2. add the missing OP_BOOLAND entry to BIP 441
3. clarify postcharging for linear operations, precharging for expensive operations, and conditional signature-check costs
4. apply the conditional signature-check formulas to BIP 441
5. update BIP 441’s reference implementation link to the gsr-core branch

I haven’t looked at this yet, because it is marked as a draft pull request. Is this still waiting for someone’s review in particular or was that perhaps an oversight?

I haven’t looked at this yet, because it is marked as a draft pull request. Is this still waiting for someone’s review in particular or was that perhaps an oversight?

This was intended, still discussing the approach with Rusty, I have now force pushed over the original commits and only applied a note describing this mixed-version resource limit issue, instead of complicating the budget calculation when mixed-version inputs are present.

I will move it to "Ready for review" when it's clear.