🧪 feat: complete BDD implementation with comprehensive documentation

Finalize BDD testing framework with:
- Unified step definitions using StepContext struct
- Proper server verification in theServerIsRunning step
- Robust JSON response handling with escaping and newline trimming
- Updated documentation reflecting current implementation
- Test validation script to ensure test quality
- All tests passing with proper black box testing

Key files updated:
- pkg/bdd/steps/steps.go: Unified step definitions
- pkg/bdd/testserver/client.go: Robust response validation
- pkg/bdd/README.md: Godog pattern guide
- doc/BDD_GUIDE.md: Updated usage guide
- adr/0008-bdd-testing.md: Updated ADR with current approach
- scripts/run-bdd-tests.sh: Test validation script

The BDD framework is now production-ready with comprehensive
documentation and proper testing practices.

pkg/bdd/testserver/client.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 )
 
 type Client struct {
@@ -46,9 +47,21 @@ func (c *Client) ExpectResponseBody(expected string) error {
 	}
 
 	actual := string(c.lastBody)
+	// Trim trailing newline if present (common in JSON responses)
+	actual = strings.TrimSuffix(actual, "\n")
+	
 	if actual != expected {
 		return fmt.Errorf("expected response body %q, got %q", expected, actual)
 	}
 
 	return nil
 }
+
+// Helper methods for debugging
+func (c *Client) GetLastResponse() *http.Response {
+	return c.lastResp
+}
+
+func (c *Client) GetLastBody() []byte {
+	return c.lastBody
+}