🧪 test: add JWT secret rotation BDD scenarios and step implementations (#12)

✨ merge: implement JWT secret rotation with BDD scenario isolation

- Implement JWT secret rotation mechanism (closes #8)
- Add per-scenario state isolation for BDD tests (closes #14)
- Validate password reset workflow via BDD tests (closes #7)
- Fix port conflicts in test validation
- Add state tracer for debugging test execution
- Document BDD isolation strategies in ADR 0025
- Fix PostgreSQL configuration environment variables

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>
Co-authored-by: Gabriel Radureau <arcodange@gmail.com>
Co-committed-by: Gabriel Radureau <arcodange@gmail.com>

pkg/jwt/jwt_secret_manager.go

@@ -0,0 +1,81 @@
+package jwt
+
+import (
+	"time"
+)
+
+// jwtSecretManagerImpl implements the JWTSecretManager interface
+type jwtSecretManagerImpl struct {
+	secrets       []JWTSecret
+	primarySecret string
+}
+
+// NewJWTSecretManager creates a new JWT secret manager
+func NewJWTSecretManager(initialSecret string) JWTSecretManager {
+	return &jwtSecretManagerImpl{
+		secrets: []JWTSecret{
+			{
+				Secret:    initialSecret,
+				IsPrimary: true,
+				CreatedAt: time.Now(),
+			},
+		},
+		primarySecret: initialSecret,
+	}
+}
+
+// AddSecret adds a new JWT secret
+func (m *jwtSecretManagerImpl) AddSecret(secret string, isPrimary bool, expiresIn time.Duration) {
+	expiresAt := time.Now().Add(expiresIn)
+	m.secrets = append(m.secrets, JWTSecret{
+		Secret:    secret,
+		IsPrimary: isPrimary,
+		CreatedAt: time.Now(),
+		ExpiresAt: &expiresAt,
+	})
+
+	if isPrimary {
+		m.primarySecret = secret
+	}
+}
+
+// RotateToSecret rotates to a new primary secret
+func (m *jwtSecretManagerImpl) RotateToSecret(newSecret string) {
+	// Mark existing primary as non-primary
+	for i, secret := range m.secrets {
+		if secret.IsPrimary {
+			m.secrets[i].IsPrimary = false
+			break
+		}
+	}
+
+	// Add new secret as primary
+	m.AddSecret(newSecret, true, 0) // No expiration for primary
+}
+
+// GetPrimarySecret returns the current primary secret
+func (m *jwtSecretManagerImpl) GetPrimarySecret() string {
+	return m.primarySecret
+}
+
+// GetAllValidSecrets returns all valid (non-expired) secrets
+func (m *jwtSecretManagerImpl) GetAllValidSecrets() []JWTSecret {
+	var validSecrets []JWTSecret
+	now := time.Now()
+
+	for _, secret := range m.secrets {
+		if secret.ExpiresAt == nil || secret.ExpiresAt.After(now) {
+			validSecrets = append(validSecrets, secret)
+		}
+	}
+
+	return validSecrets
+}
+
+// GetSecretByIndex returns a secret by index for testing
+func (m *jwtSecretManagerImpl) GetSecretByIndex(index int) (string, bool) {
+	if index < 0 || index >= len(m.secrets) {
+		return "", false
+	}
+	return m.secrets[index].Secret, true
+}