feat: implement BDD testing with Godog

Implement comprehensive BDD testing framework using Godog:
- Added feature files for greet and health endpoints
- Created test server that runs on port 9191
- Implemented step definitions using Godog's exact patterns
- Fixed undefined step warnings by following Godog conventions
- All tests passing with proper response validation
- Maintained black box testing principles

Key files:
- pkg/bdd/steps/steps.go - Step definitions using StepContext struct
- pkg/bdd/testserver/ - Test server implementation
- features/*.feature - BDD feature files
- pkg/bdd/README.md - Documentation for proper step patterns

The implementation follows Godog's exact pattern suggestions to avoid
undefined step warnings and provides comprehensive API testing.

pkg/bdd/testserver/client.go

@@ -0,0 +1,54 @@
+package testserver
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+)
+
+type Client struct {
+	server   *Server
+	lastResp *http.Response
+	lastBody []byte
+}
+
+func NewClient(server *Server) *Client {
+	return &Client{
+		server: server,
+	}
+}
+
+func (c *Client) Request(method, path string, body []byte) error {
+	url := c.server.GetBaseURL() + path
+	req, err := http.NewRequest(method, url, nil)
+	if err != nil {
+		return fmt.Errorf("failed to create request: %w", err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	c.lastResp = resp
+	c.lastBody, err = io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	return nil
+}
+
+func (c *Client) ExpectResponseBody(expected string) error {
+	if c.lastResp == nil {
+		return fmt.Errorf("no response received")
+	}
+
+	actual := string(c.lastBody)
+	if actual != expected {
+		return fmt.Errorf("expected response body %q, got %q", expected, actual)
+	}
+
+	return nil
+}

pkg/bdd/testserver/server.go

@@ -0,0 +1,104 @@
+package testserver
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	"DanceLessonsCoach/pkg/config"
+	"DanceLessonsCoach/pkg/server"
+	"github.com/rs/zerolog/log"
+)
+
+type Server struct {
+	httpServer  *http.Server
+	port       int
+	baseURL    string
+}
+
+func NewServer() *Server {
+	return &Server{
+		port: 9191,
+	}
+}
+
+func (s *Server) Start() error {
+	s.baseURL = fmt.Sprintf("http://localhost:%d", s.port)
+
+	// Create real server instance from pkg/server
+	cfg := createTestConfig(s.port)
+	realServer := server.NewServer(cfg, context.Background())
+
+	// Start HTTP server in same process
+	s.httpServer = &http.Server{
+		Addr:    fmt.Sprintf(":%d", s.port),
+		Handler: realServer.Router(),
+	}
+
+	go func() {
+		if err := s.httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			if err != http.ErrServerClosed {
+				log.Error().Err(err).Msg("Test server failed")
+			}
+		}
+	}()
+
+	// Wait for server to be ready
+	return s.waitForServerReady()
+}
+
+func (s *Server) waitForServerReady() error {
+	maxAttempts := 30
+	attempt := 0
+
+	for attempt < maxAttempts {
+		resp, err := http.Get(fmt.Sprintf("%s/api/ready", s.baseURL))
+		if err == nil && resp.StatusCode == http.StatusOK {
+			resp.Body.Close()
+			return nil
+		}
+		if resp != nil {
+			resp.Body.Close()
+		}
+		attempt++
+		time.Sleep(100 * time.Millisecond)
+	}
+
+	return fmt.Errorf("server did not become ready after %d attempts", maxAttempts)
+}
+
+func (s *Server) Stop() error {
+	if s.httpServer == nil {
+		return nil
+	}
+
+	// Shutdown HTTP server gracefully
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	return s.httpServer.Shutdown(ctx)
+}
+
+func (s *Server) GetBaseURL() string {
+	return s.baseURL
+}
+
+func createTestConfig(port int) *config.Config {
+	return &config.Config{
+		Server: config.ServerConfig{
+			Host: "localhost",
+			Port: port,
+		},
+		Shutdown: config.ShutdownConfig{
+			Timeout: 5 * time.Second,
+		},
+		Logging: config.LoggingConfig{
+			JSON:   false,
+			Level:  "trace",
+		},
+		Telemetry: config.TelemetryConfig{
+			Enabled: false,
+		},
+	}
+}