chore(openspec): archive engineering-docs and phase-2-production-ready changes

- engineering-docs → archive/2026-03-29-engineering-docs (63/63 tasks complete)
- phase-2-production-ready → archive/2026-03-29-phase-2-production-ready (89/89 tasks complete)
- openspec/specs/ synced with all Phase 1 + Phase 2 + engineering-docs capabilities (22 specs total)

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

openspec/specs/go-sdk/spec.md

@@ -0,0 +1,23 @@
+# Spec: Go SDK (`github.com/sentryagent/idp-sdk-go`)
+
+**Status**: Pending CEO approval
+**Workstream**: 3 of 8
+
+## Scope
+- `sdk-go/` directory at project root
+- Context-aware `AgentIdPClient` using standard library `net/http`
+- `TokenManager` with mutex-guarded cache and 60s auto-refresh
+- Service clients: `AgentRegistryClient`, `CredentialClient`, `TokenClient`, `AuditClient`
+- Idiomatic Go error type `AgentIdPError` implementing `error` interface
+- `go.mod` module: `github.com/sentryagent/idp-sdk-go`
+- `sdk-go/README.md`
+
+## Acceptance Criteria
+- [ ] All 14 endpoints covered
+- [ ] All methods take `context.Context` as first argument
+- [ ] No panics — all errors returned as `error`
+- [ ] `AgentIdPError` implements `error` and exposes `.Code`, `.HTTPStatus`, `.Details`
+- [ ] `TokenManager` is goroutine-safe (`sync.Mutex` on cache)
+- [ ] `go vet` and `staticcheck` pass with zero warnings
+- [ ] `go test ./...` with >80% coverage
+- [ ] README matches Node.js SDK structure