feat: Phase 1 P1 — Dockerfile, AGNTCY alignment docs, Node.js SDK

Three remaining Phase 1 P1 deliverables:

1. Dockerfile — multi-stage build (builder + production), node:18-alpine,
   non-root USER node, .dockerignore excluding secrets and dev artifacts

2. AGNTCY alignment docs (docs/agntcy/) — README and alignment.md mapping
   all 6 AGNTCY domains to AgentIdP features with Phase 2/3 pending items noted

3. Node.js SDK (@sentryagent/idp-sdk) — TypeScript strict, zero any, native
   fetch (Node 18+), TokenManager with 60s auto-refresh, service clients for
   all 14 endpoints (agents, credentials, tokens, audit), AgentIdPError typed
   error hierarchy, full README

All three changes tracked under openspec/changes/ with tasks marked complete.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

sdk/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@sentryagent/idp-sdk",
+  "version": "1.0.0",
+  "description": "Node.js SDK for SentryAgent.ai AgentIdP — typed client for agent identity management",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "prepublishOnly": "npm run build"
+  },
+  "files": [
+    "dist/"
+  ],
+  "keywords": ["sentryagent", "agentidp", "agntcy", "ai-agent", "identity"],
+  "license": "MIT",
+  "engines": {
+    "node": ">=18.0.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.4.5"
+  }
+}