feat(relay): rendezvous-relay service — 7 packages + plans (contracts/transport/agent/control-plane/e2e/auth/web)

Multi-tenant reverse-tunnel service ("ngrok for Claude Code" with E2E): a
host-agent dials OUT to an operator-run relay; external devices reach the host
THROUGH the relay, routed by per-tenant subdomain, forwarding ciphertext only
(the relay never sees plaintext). Lets a customer reach their own self-hosted
web-terminal from anywhere with zero networking setup.

Packages — all tsc-strict + vitest green (656 tests), cross-package integration verified:
- relay-contracts: frozen shared contracts (mux frame codec, data model,
  capability token, E2E envelope, pairing) — the src/types.ts analog
- term-relay:   native WS mux + stateless data plane (subdomain routing, ciphertext forward)
- agent:        host-agent (pairing, per-host Ed25519 + mTLS dial-out, forwards to 127.0.0.1:3000)
- control-plane: accounts/hosts registry, pairing-code flow, routing table, provisioning
- relay-e2e:    browser<->agent E2E (X25519 ECDH through relay, AEAD, anti-replay, recoverable replay key)
- relay-auth:   Passkey/WebAuthn, capability tokens, per-host certs, deny-by-default tenant isolation
- relay-web:    browser login + Web Crypto E2E + client-side preview rendering

Security invariants INV1-15 enforced; cross-tenant isolation CI tripwire live
(.github/workflows/relay-tripwire.yml). Design + implementation-level plans in
docs/PLAN_RELAY_*.md and docs/EXPLORE_RELAY_SERVICE.md.

NOTE: generated autonomously per the reviewed plans. The security-critical
packages (relay-e2e, relay-auth) REQUIRE expert security audit before any real
deployment — passing tests prove self-consistency, not resistance to attackers.
Base app (src/, public/) unchanged; concurrent desktop work left uncommitted.

relay-e2e/test/crypto-provider.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest'
+import { getWebCrypto, randomBytes, timingSafeEqual } from '../src/crypto-provider.js'
+import { CryptoUnavailableError } from '../src/errors.js'
+
+describe('T1 crypto-provider', () => {
+  it('getWebCrypto returns a SubtleCrypto in the node vitest environment', () => {
+    const subtle = getWebCrypto()
+    expect(typeof subtle.digest).toBe('function')
+    expect(typeof subtle.generateKey).toBe('function')
+  })
+
+  it('randomBytes(32) has length 32, differs across calls, and is not all-zero', () => {
+    const a = randomBytes(32)
+    const b = randomBytes(32)
+    expect(a.length).toBe(32)
+    expect(bytesEqual(a, b)).toBe(false)
+    expect(a.every((x) => x === 0)).toBe(false)
+  })
+
+  it('randomBytes rejects a non-integer / negative length (fail-fast)', () => {
+    expect(() => randomBytes(-1)).toThrow(CryptoUnavailableError)
+    expect(() => randomBytes(1.5)).toThrow(CryptoUnavailableError)
+  })
+
+  describe('timingSafeEqual', () => {
+    it('equal buffers → true', () => {
+      expect(timingSafeEqual(new Uint8Array([1, 2, 3]), new Uint8Array([1, 2, 3]))).toBe(true)
+    })
+    it('single-bit flip → false', () => {
+      expect(timingSafeEqual(new Uint8Array([1, 2, 3]), new Uint8Array([1, 2, 2]))).toBe(false)
+    })
+    it('length mismatch → false (no short-circuit ordering)', () => {
+      expect(timingSafeEqual(new Uint8Array([1, 2, 3]), new Uint8Array([1, 2]))).toBe(false)
+      expect(timingSafeEqual(new Uint8Array([1, 2]), new Uint8Array([1, 2, 3]))).toBe(false)
+    })
+    it('empty buffers → true', () => {
+      expect(timingSafeEqual(new Uint8Array(0), new Uint8Array(0))).toBe(true)
+    })
+  })
+})
+
+function bytesEqual(a: Uint8Array, b: Uint8Array): boolean {
+  if (a.length !== b.length) return false
+  return a.every((x, i) => x === b[i])
+}