Add ecash payment, Cashu wallet, and admin UI

[nisfeb]

Summary

• Ecash payment support: maintainers can require sats-per-PR, committers load wallets via Lightning from a Cashu mint, tokens are automatically selected and included in commit signatures
• NUT-03 swap verification: the maintainer's ship swaps incoming tokens at the mint during verify-commit to confirm their value before passing CI — no blind trust
• Sail admin UI: server-rendered panel at /vitriol/admin split into committer (wallet, mint config, load sats) and maintainer (payment toggle, price, ban list, ecash pubkey) sections, plus a landing page at /vitriol

What changed

Agent (desk/app/vitriol.hoon)

• State-6 with wallet, mint URL, keyset cache, sats-per-pr price, pending mints, pending verifications
• Curve25519 encryption keypair generation for future DH ecash exchange
• Committer wallet flow: configure mint → request Lightning invoice (NUT-04) → poll via Behn timers → mint tokens → store proofs
• /sign accepts sats_required, selects proofs from wallet (≥ required, ≤ 110%), deducts from wallet
• /verify-commit parses incoming ecash tokens, initiates NUT-03 swap at the mint, returns verify_id for async polling
• /verify-status/{id} polling endpoint for CI to await swap completion
• /sats-per-pr endpoint exposes maintainer's price
• Tokens accepted even when payment not required
• All endpoints behind Eyre auth (403 otherwise)

Cashu library (desk/lib/cashu.hoon)

• Full BDHKE implementation (NUT-00) with secp256k1 via fo modular arithmetic
• NUT-03 swap, NUT-04 mint via Lightning, NUT-05 melt
• Hash-to-curve, point compression/decompression, keyset parsing, amount splitting

Admin UI (desk/lib/vitriol-ui.hoon)

• Sail pages with dark theme
• Committer section: wallet balance, mint URL, load sats form
• Maintainer section: payment toggle, sats-per-PR price input, ecash pubkey display, ban list with add/remove
• Landing page with endpoint reference

Types (desk/sur/vitriol.hoon)

• cashu-proof, pending-mint-quote, pending-verify

Hook (hooks/groundwire-sign)

• Fetches maintainer's sats-per-pr price
• Passes sats_required to /sign
• Includes ecash-amount and ecash-tokens in signature block
• Handles error responses (insufficient balance, etc.)

Other

• sys.kelvin: supports both 408 and 409
• install.sh: updated docs for maintainer ecash flow
• README.md: comprehensive rewrite

Token flow

committer                    maintainer                   cashu mint
    |                            |                            |
 load sats               set sats-per-pr                     |
 via Lightning           in admin panel                      |
    |                            |                            |
 git commit ──────> hook fetches price ──────────────────>   |
    |               from /sats-per-pr                        |
    |                            |                            |
 /sign selects      verify-commit receives                   |
 tokens from        tokens + mint URL                        |
 wallet (≤110%)          |                                   |
    |               NUT-03 swap ──────────────────────> validates
    |               (blind, send, unblind)              & signs
    |                            |                       new proofs
    |               swap succeeds ────────────────────>  |
    |               → tokens stored in wallet            |
    |               → CI returns verified                |

Test plan

• Set mint URL in admin panel, load sats via Lightning invoice
• Verify wallet balance updates after payment
• Set sats-per-pr price in maintainer admin
• Sign a commit with sats_required — tokens selected and deducted
• Verify token selection respects 110% cap
• Submit tokens via verify-commit — NUT-03 swap succeeds
• Poll verify-status until verified
• Test with payment not required but tokens included (should accept)
• Test insufficient balance error
• Verify all endpoints return 403 without auth cookie
• Confirm ban list blocks verification even with valid signature
• Test state migration from state-4/5 to state-6

🤖 Generated with Claude Code

[github-actions]

Groundwire Verification Failed

This PR will not be reviewed because commits are not signed by a recognized Groundwire ID.

UNSIGNED 0b8e7ab3

Why?

This repository requires contributors to prove ownership of an onchain Groundwire identity.
Commit signatures are cryptographically verified against the signer's on-chain networking key.

How to fix this

1. Get a Groundwire ID — groundwire.network/get-started
2. Install commit signing — ./hooks/install.sh <your-ship-url>
3. Re-sign your commits — git rebase --exec "true" HEAD~N (after configuring signing)

---

This repository is protected by Groundwire for GitHub.