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.

control-plane/src/registry/accounts.ts

@@ -0,0 +1,63 @@
+/**
+ * T3 — account registry (immutable, INV8). `createAccount` writes a version-1 snapshot;
+ * `setAccountStatus` performs the atomic append-version + pointer-swap (prior snapshot stays
+ * readable from `versions()`). Never mutates a lifecycle field in place.
+ */
+import type { AccountRecord, AccountStatus } from '../model/records.js'
+import type { AccountStore } from '../store/ports.js'
+import type { AuditWriter } from '../audit/log.js'
+import { noopAuditWriter } from '../audit/log.js'
+import type { PlanTier } from 'relay-contracts'
+import { newUuid, nowIso } from '../util/ids.js'
+
+export interface AccountRegistry {
+  createAccount(plan: PlanTier): Promise<AccountRecord>
+  getAccount(accountId: string): Promise<AccountRecord | null>
+  setAccountStatus(accountId: string, status: AccountStatus): Promise<AccountRecord>
+}
+
+export interface AccountRegistryDeps {
+  readonly accounts: AccountStore
+  readonly audit?: AuditWriter
+  readonly actor?: string
+}
+
+export function createAccountRegistry(deps: AccountRegistryDeps): AccountRegistry {
+  const audit = deps.audit ?? noopAuditWriter()
+  const actor = deps.actor ?? 'system'
+  return {
+    async createAccount(plan) {
+      const rec: AccountRecord = {
+        accountId: newUuid(), // unguessable, never recycled (INV1 precondition)
+        plan,
+        createdAt: nowIso(),
+        status: 'active',
+      }
+      await deps.accounts.insert(rec)
+      await audit.writeAuditEvent({
+        action: 'account.create',
+        principalId: actor,
+        accountId: rec.accountId,
+        hostId: null,
+        ts: rec.createdAt,
+        meta: { plan },
+      })
+      return rec
+    },
+    async getAccount(accountId) {
+      return deps.accounts.get(accountId)
+    },
+    async setAccountStatus(accountId, status) {
+      const next = await deps.accounts.swapStatus(accountId, status, actor) // NEW snapshot, atomic swap
+      await audit.writeAuditEvent({
+        action: status === 'suspended' ? 'account.suspend' : 'manage',
+        principalId: actor,
+        accountId,
+        hostId: null,
+        ts: nowIso(),
+        meta: { status },
+      })
+      return next
+    },
+  }
+}