refactor(pxe): nameless wire-structural labels and ResolvedTx cleanup

[nchamo]

Summary

Follow-up to #24752, folding in cleanup that belongs with it:

• Labels are now wire-structural. A struct's label drops its field names and splices nested struct labels into the parent ({field,u32}), so a label encodes exactly what the wire does: anything the wire tolerates (a field rename, a struct-in-struct nesting refactor) no longer moves the interface hash, and a genuine layout change still does. camelToSnake is gone with it.
• ResolvedTx becomes a plain type. refactor(pxe): compute oracle interface hash from mapping labels #24752 moved its wire layout into the RESOLVED_TX struct mapping, which orphaned the class's toFields(). The class, its inline-data pin test, and the Noir resolved_tx_serialization_matches_typescript counterpart are deleted — the generated oracle tests already verify that wire end-to-end.
• RETRACTABLE_FACT_ORIGIN.blockState maps as a validated origin-block-state scalar instead of the U32 placeholder, following the same honest-types direction as the BYTE → U8 rename in refactor(pxe): compute oracle interface hash from mapping labels #24752.

Both interface hashes (PXE and TXE) are re-pinned; the wire is unchanged, so the oracle versions are untouched.