✨ feat(server): add /api/healthz endpoint with rich health info

Adds a Kubernetes-style healthz endpoint returning status, version,
uptime_seconds and timestamp. Non-breaking — /api/health is preserved.

- New route: GET /api/healthz
- New handler: handleHealthz with HealthzResponse struct
- New unit test: pkg/server/healthz_test.go (passes locally)
- New BDD scenario: features/health/health.feature
- BDD steps: pkg/bdd/steps/health_steps.go, common_steps.go

Note: BDD tests require Postgres and will be validated by CI.

🤖 Co-Authored-By: Mistral Vibe (devstral-2 / mistral-medium-3.5)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/bdd/steps/common_steps.go

@@ -63,3 +63,39 @@ func (s *CommonSteps) theStatusCodeShouldBe(expectedStatus int) error {
 	}
 	return nil
 }
+
+// JSON field validation
+func (s *CommonSteps) theResponseShouldBeJSONWithFields(fields string) error {
+	// Parse the fields comma-separated list
+	fieldList := strings.Split(fields, ", ")
+	for _, field := range fieldList {
+		field = strings.TrimSpace(field)
+		if !s.responseContainsJSONField(field) {
+			return fmt.Errorf("response does not contain field %q", field)
+		}
+	}
+	return nil
+}
+
+func (s *CommonSteps) responseContainsJSONField(field string) bool {
+	body := string(s.client.GetLastBody())
+	// Simple check - look for "field":" in the JSON
+	// This works for simple fields, may need enhancement for nested objects
+	searchString := `"` + field + `":`
+	return strings.Contains(body, searchString)
+}
+
+func (s *CommonSteps) theFieldShouldEqual(field, expectedValue string) error {
+	body := string(s.client.GetLastBody())
+	// Look for the field and extract its value
+	// Simple implementation: look for "field":"value" pattern
+	searchPattern := `"` + field + `":"` + expectedValue + `"`
+	if !strings.Contains(body, searchPattern) {
+		// Also try without quotes (for numbers)
+		searchPatternNum := `"` + field + `":` + expectedValue
+		if !strings.Contains(body, searchPatternNum) {
+			return fmt.Errorf("field %q does not equal %q in response: %s", field, expectedValue, body)
+		}
+	}
+	return nil
+}

pkg/bdd/steps/health_steps.go

@@ -24,6 +24,10 @@ func (s *HealthSteps) iRequestTheHealthEndpoint() error {
 	return s.client.Request("GET", "/api/health", nil)
 }
 
+func (s *HealthSteps) iRequestTheHealthzEndpoint() error {
+	return s.client.Request("GET", "/api/healthz", 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)

pkg/bdd/steps/steps.go

@@ -83,6 +83,7 @@ func InitializeAllSteps(ctx *godog.ScenarioContext, client *testserver.Client, s
 
 	// Health steps
 	ctx.Step(`^I request the health endpoint$`, sc.healthSteps.iRequestTheHealthEndpoint)
+	ctx.Step(`^I request the healthz endpoint$`, sc.healthSteps.iRequestTheHealthzEndpoint)
 	ctx.Step(`^the server is running$`, sc.healthSteps.theServerIsRunning)
 
 	// Auth steps
@@ -297,4 +298,6 @@ func InitializeAllSteps(ctx *godog.ScenarioContext, client *testserver.Client, s
 	ctx.Step(`^the response should be "{\\"([^"]*)":\\"([^"]*)"}"$`, sc.commonSteps.theResponseShouldBe)
 	ctx.Step(`^the response should contain error "([^"]*)"$`, sc.commonSteps.theResponseShouldContainError)
 	ctx.Step(`^the status code should be (\d+)$`, sc.commonSteps.theStatusCodeShouldBe)
+	ctx.Step(`^the response should be JSON with fields "([^"]*)"$`, sc.commonSteps.theResponseShouldBeJSONWithFields)
+	ctx.Step(`^the "([^"]*)" field should equal "([^"]*)"$`, sc.commonSteps.theFieldShouldEqual)
 }