Phase 4 (continued): Archive upload orchestration + GHES version checker

- Archive uploader (pkg/archive/uploader.go): Priority-based routing — GitHub-owned > AWS > Azure > error. Validates credentials and dispatches to appropriate storage client. 10 tests.
- GHES version checker (pkg/ghes/version.go): Determines if GHES instance requires blob storage credentials (< 3.8.0) or can use GitHub-owned storage (>= 3.8.0). Local semver parsing. 7 tests.

Author: offbyone

pkg/archive/uploader.go

@@ -0,0 +1,150 @@
+// Package archive provides orchestration for uploading migration archives
+// to the appropriate storage backend.
+package archive
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/github/gh-gei/pkg/logger"
+)
+
+// AzureUploader uploads an archive to Azure Blob Storage.
+type AzureUploader interface {
+	Upload(ctx context.Context, fileName string, content io.Reader, size int64) (string, error)
+}
+
+// AWSUploader uploads an archive to AWS S3.
+type AWSUploader interface {
+	Upload(ctx context.Context, bucket, key string, data io.Reader) (string, error)
+}
+
+// GitHubUploader uploads an archive to GitHub-owned storage.
+type GitHubUploader interface {
+	Upload(ctx context.Context, orgDatabaseID, archiveName string, content io.ReadSeeker, size int64) (string, error)
+}
+
+// OrgIDResolver resolves an organization login to its database ID.
+type OrgIDResolver interface {
+	GetOrganizationDatabaseId(ctx context.Context, org string) (string, error)
+}
+
+// Uploader coordinates archive uploads across storage backends.
+// Priority follows the C# original: GitHub-owned > AWS S3 > Azure Blob.
+type Uploader struct {
+	azure         AzureUploader
+	aws           AWSUploader
+	awsBucket     string
+	github        GitHubUploader
+	orgIDResolver OrgIDResolver
+	logger        *logger.Logger
+}
+
+// UploaderOption configures an Uploader.
+type UploaderOption func(*Uploader)
+
+// WithAzure configures Azure Blob Storage as an upload backend.
+func WithAzure(a AzureUploader) UploaderOption {
+	return func(u *Uploader) {
+		u.azure = a
+	}
+}
+
+// WithAWS configures AWS S3 as an upload backend.
+func WithAWS(a AWSUploader, bucket string) UploaderOption {
+	return func(u *Uploader) {
+		u.aws = a
+		u.awsBucket = bucket
+	}
+}
+
+// WithGitHub configures GitHub-owned storage as an upload backend.
+func WithGitHub(g GitHubUploader, resolver OrgIDResolver) UploaderOption {
+	return func(u *Uploader) {
+		u.github = g
+		u.orgIDResolver = resolver
+	}
+}
+
+// WithLogger sets the logger for upload progress messages.
+func WithLogger(l *logger.Logger) UploaderOption {
+	return func(u *Uploader) {
+		u.logger = l
+	}
+}
+
+// NewUploader creates an Uploader with the given options.
+func NewUploader(opts ...UploaderOption) *Uploader {
+	u := &Uploader{}
+	for _, opt := range opts {
+		opt(u)
+	}
+	return u
+}
+
+// Upload uploads the archive to the highest-priority configured backend.
+// Priority: GitHub-owned storage > AWS S3 > Azure Blob Storage.
+// Returns the URL of the uploaded archive.
+func (u *Uploader) Upload(ctx context.Context, targetOrg, fileName string, content io.ReadSeeker, size int64) (string, error) {
+	if u.github != nil {
+		return u.uploadToGitHub(ctx, targetOrg, fileName, content, size)
+	}
+
+	if u.aws != nil {
+		return u.uploadToAWS(ctx, fileName, content)
+	}
+
+	if u.azure != nil {
+		return u.uploadToAzure(ctx, fileName, content, size)
+	}
+
+	return "", fmt.Errorf("no upload destination configured; provide Azure, AWS, or GitHub-owned storage credentials")
+}
+
+func (u *Uploader) uploadToGitHub(ctx context.Context, targetOrg, fileName string, content io.ReadSeeker, size int64) (string, error) {
+	u.logInfo("Uploading archive %s to GitHub-owned storage", fileName)
+
+	orgDatabaseID, err := u.orgIDResolver.GetOrganizationDatabaseId(ctx, targetOrg)
+	if err != nil {
+		return "", fmt.Errorf("resolving org database ID for %q: %w", targetOrg, err)
+	}
+
+	url, err := u.github.Upload(ctx, orgDatabaseID, fileName, content, size)
+	if err != nil {
+		return "", err
+	}
+
+	u.logInfo("Upload complete")
+	return url, nil
+}
+
+func (u *Uploader) uploadToAWS(ctx context.Context, fileName string, content io.Reader) (string, error) {
+	u.logInfo("Uploading archive %s to AWS", fileName)
+
+	url, err := u.aws.Upload(ctx, u.awsBucket, fileName, content)
+	if err != nil {
+		return "", err
+	}
+
+	u.logInfo("Upload complete")
+	return url, nil
+}
+
+func (u *Uploader) uploadToAzure(ctx context.Context, fileName string, content io.Reader, size int64) (string, error) {
+	u.logInfo("Uploading archive %s to Azure Blob Storage", fileName)
+
+	url, err := u.azure.Upload(ctx, fileName, content, size)
+	if err != nil {
+		return "", err
+	}
+
+	u.logInfo("Upload complete")
+	return url, nil
+}
+
+func (u *Uploader) logInfo(format string, args ...interface{}) {
+	if u.logger != nil {
+		u.logger.Info(format, args...)
+	}
+}