test: add S3 Tables test infrastructure

- Create setup.go with TestCluster and S3TablesClient definitions
- Create client.go with HTTP client methods for all operations
- Test utilities and client methods organized for reusability
- Foundation for S3 Tables integration tests

test/s3tables/setup.go

@@ -0,0 +1,51 @@
+package s3tables
+
+import (
+	"context"
+	"net/http"
+	"sync"
+	"time"
+)
+
+// TestCluster manages the weed mini instance for integration testing
+type TestCluster struct {
+	dataDir    string
+	ctx        context.Context
+	cancel     context.CancelFunc
+	isRunning  bool
+	startOnce  sync.Once
+	wg         sync.WaitGroup
+	masterPort int
+	volumePort int
+	filerPort  int
+	s3Port     int
+	s3Endpoint string
+}
+
+// S3TablesClient is a simple client for S3 Tables API
+type S3TablesClient struct {
+	endpoint  string
+	region    string
+	accessKey string
+	secretKey string
+	client    *http.Client
+}
+
+// NewS3TablesClient creates a new S3 Tables client
+func NewS3TablesClient(endpoint, region, accessKey, secretKey string) *S3TablesClient {
+	return &S3TablesClient{
+		endpoint:  endpoint,
+		region:    region,
+		accessKey: accessKey,
+		secretKey: secretKey,
+		client:    &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
+// Test configuration constants
+const (
+	testRegion    = "us-west-2"
+	testAccessKey = "admin"
+	testSecretKey = "admin"
+	testAccountID = "111122223333"
+)