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>

tsconfig.base.json

@@ -0,0 +1,21 @@
+{
+  "compilerOptions": {
+    "target": "ES2023",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "lib": ["ES2023"],
+    "strict": true,
+    "esModuleInterop": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "exactOptionalPropertyTypes": true,
+    "forceConsistentCasingInFileNames": true,
+    "skipLibCheck": true,
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "composite": true,
+    "isolatedModules": true,
+    "verbatimModuleSyntax": true
+  }
+}