feat: add ZK Proof Service Real cryptographic compute via MPP

[Himess]

New Service: ZK Proof Service

Live: https://himess-zk-proof-service.hf.space
Source: https://github.com/Himess/zk-proof-service
llms.txt: https://himess-zk-proof-service.hf.space/llms.txt

What it does

Generates Groth16 zero-knowledge proofs for private UTXO transactions. This is real cryptographic computation — 13,726 constraints, elliptic curve pairings on BN254 — not an API proxy. Agents send circuit inputs, pay via MPP, and get back a proof ready for on-chain Solidity verifiers.

Endpoints

Route	Price	Description
GET /circuits	Free	List circuits and pricing
POST /prove/1x2	$0.01	1-input 2-output JoinSplit proof (13,726 constraints)
POST /prove/2x2	$0.02	2-input 2-output JoinSplit proof (25,877 constraints)
POST /verify/1x2	Free	Verify a proof
POST /verify/2x2	Free	Verify a proof

Stack

• Engine: snarkjs Groth16 + BN254 curve
• Server: Hono + mppx (first-party MPP integration)
• Payment: MPP (USDC on Tempo), per-proof charging via 402 flow
• Hosting: Hugging Face Spaces (16GB RAM)
• Extras: MCP server for Claude/Cursor, llms.txt for agent discovery

Performance

• Proof generation: ~2-5s (warm)
• Verification: ~50ms
• Output includes contractProof (uint256[8]) for direct Solidity verifyProof() calls

Verified

$ tempo request -t https://himess-zk-proof-service.hf.space/circuits
  1x2: $0.01, 2x2: $0.02

$ tempo request -v -X POST -H "Content-Type: application/json" \
    -d @input.json https://himess-zk-proof-service.hf.space/prove/1x2
  Paid 0.01 USDC · 0x68ec5052...
  { proof: { pi_a, pi_b, pi_c }, generationTimeMs: 2031 }

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