Add remote storage backend

internal/adapters/storage/factory.go

@@ -0,0 +1,29 @@
+package storage
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/narratio/internal/config"
+)
+
+// NewObjectStoreFromConfig constructs a remote object store from resolved config.
+func NewObjectStoreFromConfig(ctx context.Context, cfg *config.Config) (ObjectStore, error) {
+	if cfg == nil || cfg.Pipeline == nil {
+		return nil, fmt.Errorf("pipeline config is required")
+	}
+
+	if strings.EqualFold(strings.TrimSpace(cfg.Pipeline.Storage.Backend), "s3") {
+		if cfg.Pipeline.Storage.S3 == nil {
+			return nil, fmt.Errorf("pipeline.storage.s3 is required when pipeline.storage.backend is s3")
+		}
+		return NewS3BackendFromConfig(ctx, *cfg.Pipeline.Storage.S3)
+	}
+
+	if cfg.Pipeline.Storage.S3 != nil && strings.TrimSpace(cfg.Pipeline.Storage.S3.Bucket) != "" {
+		return NewS3BackendFromConfig(ctx, *cfg.Pipeline.Storage.S3)
+	}
+
+	return nil, fmt.Errorf("no remote object store backend is configured")
+}