routing: Directly call Kemal's add_route function

src/invidious/routing.cr

@@ -4,7 +4,11 @@ module Invidious::Routing
   {% for http_method in {"get", "post", "delete", "options", "patch", "put"} %}
 
     macro {{http_method.id}}(path, controller, method = :handle)
-      {{http_method.id}} \{{ path }} do |env|
+      unless !Kemal::Utils.path_starts_with_slash?(\{{path}})
+        raise Kemal::Exceptions::InvalidPathStartException.new({{http_method}}, \{{path}})
+      end
+
+      Kemal::RouteHandler::INSTANCE.add_route({{http_method.upcase}}, \{{path}}) do |env|
         \{{ controller }}.\{{ method.id }}(env)
       end
     end