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/src/index.ts

@@ -0,0 +1,35 @@
+export { AgentIdPClient } from './client.js';
+export { AgentIdPError } from './errors.js';
+export { TokenManager } from './token-manager.js';
+
+export type {
+  // Config
+  AgentIdPClientConfig,
+  // Enums / union types
+  AgentType,
+  AgentStatus,
+  DeploymentEnv,
+  CredentialStatus,
+  OAuthScope,
+  AuditAction,
+  AuditOutcome,
+  // Agent Registry
+  Agent,
+  RegisterAgentRequest,
+  UpdateAgentRequest,
+  ListAgentsParams,
+  PaginatedAgents,
+  // Credentials
+  Credential,
+  CredentialWithSecret,
+  GenerateCredentialRequest,
+  ListCredentialsParams,
+  PaginatedCredentials,
+  // Tokens
+  TokenResponse,
+  IntrospectResponse,
+  // Audit
+  AuditEvent,
+  QueryAuditLogParams,
+  PaginatedAuditEvents,
+} from './types.js';