Optimize DPF/PPRF and harden reusable RevCuckoo

[ladnir]

Restore the DPF/PPRF optimizations and reusable RevCuckoo changes from #188 for continued protocol review after their revert from master.

Regular DPF/PPRF expansion uses compact tree storage and explicit batched kernels. HalfTree uses the paper's orthomorphism hash and pipelines eight AES chains with paired preparation of the next batch. RevCuckoo retains reusable position setup, refreshed payload masks, and the hash-width and sparse-tree fixes. Local protocol tests queue socket continuations to avoid native-stack exhaustion under GCC/ASan.

The cryptoTools pin includes the Edwards25519 decoding correction already merged upstream in cryptoTools #50.

This draft contains only the restored #188 changes. The silent-LPN changes from #189 and FOLEAGE/AnyField additions from #190 are deferred. Waterfall remains absent.

Validation

• Verified that the complete committed tree, including the cryptoTools pin, exactly matches the original Optimize DPF/PPRF and harden reusable RevCuckoo #188 merge (c1b3afb).
• CI on that identical tree passed.
• New CI will run for this draft. No new implementation changes or benchmark measurements are included in this restoration.

Review focus: protocol correctness and privacy under supported parameters, including repeated expansions and randomness reuse.