feat(note-transport): add verified note submission

[kkovaacs]

Summary

• Add a new SendNoteWithProof endpoint to verify inclusion against a configured trusted node before storing notes. Cache note root commitments fetched from the trusted node with a bounded LRU and retry transient lookups within the request timeout budget.
• Distinguish unverified after_block_num hints from verified included_in_block values in fetch responses and storage.

Changelog

[[entry]]
scope       = "note-transport"
impact      = "breaking"
description = "Added new `SendNoteWithProof` endpoint requiring inclusion proofs for submitted notes."

[igamigo]

LGTM. I didn't look too much into this but the two endpoint variants require note details that quite closely resemble what the variants in NoteFile represent (https://github.com/0xMiden/protocol/blob/next/crates/miden-standards/src/note/file.rs#L75-L95) so I wonder if it's possible to reuse those messages.

[igamigo]

Should we make this non-optional? I don't believe there is currently any value in it being optional at all, but maybe I'm missing something

[kkovaacs]

We just kept the behavior of the note transport layer, where this has been optional. Are you saying that the client is always sending the after_block_num hint?

[igamigo]

Can this be a oneof? Not sure if the plan is to keep SendNote or not

[kkovaacs]

There are two ways forward:

1. We remove SendNote and keep only the verified submission path. In that case I wouldn't convert this to a oneof.
2. @bobbinth suggested that we can also keep SendNote but keep unverified notes only for a short time (a few minutes). If the note is not included on chain within that time we'd just remove them. Personally I think having both paths is a bit overlapping in functionality.

The second route basically wouldn't need changes in the client -- you could still submit notes without a proof and the note transport layer would take care of checking which of those get included on chain (and evict the rest).

However, if we change the client to wait for inclusion before submitting the note there's now point in keeping SendNote IMO.