P1 spine: monorepo, shared WS protocol, server daemon

- npm workspaces (shared / server / web), TS strict, project refs
- @arboretum/shared: multiplexed WS protocol (JSON control + binary
  output frames: 1B type + u32le channel), flow-control constants
  (ACK 256K, HIGH 384K, LOW 128K, lagging 2M), REST types
- git-arboretum server: Fastify 5 + node:sqlite (single native dep:
  node-pty prebuilt), token auth (sha256 at rest, HMAC cookie, global
  login rate limit + backoff), strict Origin check on /api and /ws,
  PtyManager (2MiB ring with monotonic offset, resync replay = reset +
  256KiB tail, pause/resume only when ALL interactive clients exceed
  HIGH, observers never throttle, lagging clients resync), WS gateway
  (attach/stdin/resize/ack, heartbeat 30s), SIGTERM→SIGKILL 5s grace
- CLI: arboretum [--port 7317] [--bind 127.0.0.1] — non-loopback bind
  requires an explicit safety flag
- Smoke-tested: login/401/403-origin/spawn bash/kill/grace-SIGKILL all
  green

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/shared/src/api.ts

@@ -0,0 +1,31 @@
+// Types REST partagés (préfixe /api/v1) — sous-ensemble P1.
+import type { SessionSummary } from './protocol.js';
+
+export interface ApiError {
+  error: { code: string; message: string; details?: unknown };
+}
+
+export interface LoginRequest {
+  token: string;
+}
+export interface LoginResponse {
+  ok: true;
+  label: string;
+}
+export interface MeResponse {
+  ok: true;
+  tokenLabel: string;
+  serverVersion: string;
+}
+
+export interface CreateSessionRequest {
+  cwd: string;
+  /** binaire à lancer — défaut "claude" ; "bash" sert aux tests d'acceptation sans quota */
+  command?: 'claude' | 'bash';
+}
+export interface SessionsListResponse {
+  sessions: SessionSummary[];
+}
+export interface SessionResponse {
+  session: SessionSummary;
+}