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>

openspec/changes/agntcy-alignment-docs/tasks.md

@@ -0,0 +1,17 @@
+## 1. docs/agntcy/README.md
+
+- [x] 1.1 Write intro: what AGNTCY is (Linux Foundation, AI agent interoperability standard)
+- [x] 1.2 Write why it matters: standardised agent identity, cross-system interoperability
+- [x] 1.3 Link to alignment.md
+
+## 2. docs/agntcy/alignment.md
+
+- [x] 2.1 Write AGNTCY core concepts section: non-human identity, agent registry, credential management, lifecycle, audit
+- [x] 2.2 Write AgentIdP implementation mapping table: each AGNTCY concept → AgentIdP feature → API endpoint
+- [x] 2.3 Write compliance status section: what is implemented (Phase 1), what is pending (Phase 2+)
+- [x] 2.4 Write interoperability section: how AgentIdP-registered agents can be identified by other AGNTCY-compliant systems
+
+## 3. QA
+
+- [x] 3.1 Verify all API endpoints referenced in the mapping table exist
+- [x] 3.2 Verify compliance status is honest — no overclaiming