refactor(healthcheck): streamline health check configuration and defaults

- Moved health check constants from common package alongside type definition.
- Updated health check configuration to use struct directly instead of pointers.
- Introduced global default health check config

internal/types/routes.go

@@ -29,7 +29,7 @@ type (
 		Started() <-chan struct{}
 
 		IdlewatcherConfig() *IdlewatcherConfig
-		HealthCheckConfig() *HealthCheckConfig
+		HealthCheckConfig() HealthCheckConfig
 		LoadBalanceConfig() *LoadBalancerConfig
 		HomepageItem() homepage.Item
 		DisplayName() string