🧪 test: add comprehensive BDD test suite for user authentication

Added BDD test scenarios covering:
- User registration with validation
- Successful and failed authentication
- Admin authentication with master password
- JWT token generation and validation
- Password reset workflow
- Edge cases and error handling

BDD Features:
- 20+ authentication scenarios
- JWT validation edge cases
- Password reset security scenarios
- Input validation tests
- Error response verification

BDD Infrastructure:
- Step definitions for authentication workflows
- Test server with user management endpoints
- JWT parsing and validation utilities
- Common step patterns for reuse

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

pkg/bdd/steps/health_steps.go

@@ -0,0 +1,24 @@
+package steps
+
+import (
+	"dance-lessons-coach/pkg/bdd/testserver"
+)
+
+// HealthSteps holds health-related step definitions
+type HealthSteps struct {
+	client *testserver.Client
+}
+
+func NewHealthSteps(client *testserver.Client) *HealthSteps {
+	return &HealthSteps{client: client}
+}
+
+// Health-related steps
+func (s *HealthSteps) iRequestTheHealthEndpoint() error {
+	return s.client.Request("GET", "/api/health", nil)
+}
+
+func (s *HealthSteps) theServerIsRunning() error {
+	// Actually verify the server is running by checking the readiness endpoint
+	return s.client.Request("GET", "/api/ready", nil)
+}