feat(storage-minio): initial implementation — MinIO/S3 object storage with lifecycle (v1.0.0)

Introduces code.nochebuena.dev/einherjar/storage-minio — the object storage
starter for the Einherjar framework. Absorbs the minio package from micro-lib,
replacing fmt.Errorf wrapping with core/xerrors.

Interfaces (CT-6: one TypeSpec per file):
- Provider — PutObject, RemoveObject, GetObject, PresignedGetObject, HandleError
- Component — lifecycle.Component + observability.Checkable + Provider + Native()

Implementation:
- New(logger, cfg) Component — client not created until OnInit
- OnInit: minio.New with credentials and transport; bucket existence check
- OnStart: BucketExists PING; logs "minio: connected"
- OnStop: logs "minio: closing client" (minio-go is stateless; no explicit close)
- HealthCheck: BucketExists check; Priority LevelCritical
- Native() *miniogo.Client — escape hatch for operations not in Provider
- HandleError: maps minio-go errors to xerrors (NotFound, AlreadyExists, Internal)

Config (EINHERJAR_MINIO_* env vars):
  Endpoint(required), AccessKey(required), SecretKey(required),
  Bucket(required), UseSSL(false), Region(us-east-1)

- Component interface embeds observability.Identifiable; identifiable.go implements
  ModulePath and ModuleVersion via runtime/debug.ReadBuildInfo() — prints in launcher banner

component.go

@@ -0,0 +1,19 @@
+package minio
+
+import (
+	miniogo "github.com/minio/minio-go/v7"
+
+	"code.nochebuena.dev/einherjar/contracts/lifecycle"
+	"code.nochebuena.dev/einherjar/contracts/observability"
+)
+
+// Component bundles lifecycle management, health checks, and MinIO client operations.
+// Register with the launcher and health aggregator before starting.
+type Component interface {
+	lifecycle.Component
+	observability.Checkable
+	observability.Identifiable
+	Provider
+	// Native returns the underlying minio-go SDK client for operations not covered by Provider.
+	Native() *miniogo.Client
+}