phase 2 (part 1): OpenAPI-generated API server, first 9 endpoints

- api/openapi.yaml converted 3.1 → 3.0.3 (oapi-codegen/kin-openapi
  supports 3.0; nullable syntax + example keywords), still redocly-clean
- oapi-codegen (v2.4.1, strict server + chi) generates
  internal/httpapi/gen from the spec; `make generate` wired
- internal/httpapi: chi router, /healthz (unauthenticated, SG18),
  RFC 9457 problem+json mapping from domain sentinels (SG11), 5xx detail
  logged server-side only, request logging with request IDs, graceful
  shutdown (SG4), interim static bearer auth (constant-time; dev-open
  when no token; OIDC JWT still to come in Phase 2)
- Implemented: listEntities (type filter walks the hierarchy, keyset
  pagination), getEntity (UUID or slug, ETag), getEntityRelations,
  getBlastRadius, getGraph (nodes+edges for UIs), getOntology,
  listSignals, getFleetHealth, exportSeeds. Remaining 38 ops return 501
  problem+json stubs (compiler-enforced interface completeness)
- `oikos api` role live: migrate-on-start, serves :8090
- 15 API integration tests (auth, pagination, hierarchy filter, ETag,
  404/501 problem shapes, graph, export)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

go.mod

@@ -3,17 +3,25 @@ module github.com/dtoro/oikos
 go 1.26.3
 
 require (
+	github.com/getkin/kin-openapi v0.140.0
+	github.com/go-chi/chi/v5 v5.3.1
 	github.com/google/uuid v1.6.0
 	github.com/jackc/pgx/v5 v5.10.0
+	github.com/oapi-codegen/runtime v1.4.2
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/apapsch/go-jsonmerge/v2 v2.0.0 // indirect
+	github.com/go-openapi/jsonpointer v0.22.5 // indirect
+	github.com/go-openapi/swag/jsonname v0.25.5 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
-	github.com/kr/text v0.2.0 // indirect
+	github.com/oasdiff/yaml v0.1.0 // indirect
+	github.com/oasdiff/yaml3 v0.0.13 // indirect
 	github.com/rogpeppe/go-internal v1.15.0 // indirect
-	golang.org/x/sync v0.17.0 // indirect
-	golang.org/x/text v0.29.0 // indirect
+	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2 // indirect
+	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/text v0.32.0 // indirect
 )