ADR 011 - Optimistic Blob Size Independent Inclusion Proofs and PFB Fraud Proofs

[nashqueue]

Overview

This PR Looks at the possibility to use pfd-transactions for message inclusion proofs. It also introduces pfd-fraud-proofs.

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PRs should be left in Draft until the below checklist is completed.
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[rootulp]

Sorry for prematurely reviewing a draft PR, I get excited when I see your ADRs

[rootulp]

My feedback is mostly questions for me to better understand

[musalbas]

Here's my attempt at a tl;dr of this:
Instead of light clients verifying that a commitment was inside the data root, they simply check if there's a PFB with that commitment, and rely on fraud proofs if 2/3 of validators included invalid PFBs. The fraud proof is a Merkle proof of the expected subroot locations in the data root, which you can check don't match the PFB's commitment.

This doesn't require any consensus-critical changes to celestia-core/app though however, right? Also the fraud proof could be done on the rollup/rollmint level.

[nashqueue]

@evan-forbes The ADR does not change core because we declined on doing optimization 1 & 2 as it is not that good for a tradeoff for the effort. That's why there is no blocker in merging this imo.