Add dedicated configuration for skipping Tilt

Having to pass `render: false` when registering Rodauth configurations can be a
bit awkward when the developer isn't otherwise exposed with Rodauth being a Roda
plugin. Moreover, it can be cumbersome, because it needs to be passed for every
Rodauth configuration.

Having dedicated configuration makes it much more straighforward to skip Tilt,
and this way it doesn't get mixed with things that actually affect
authentication behavior or calling Rodauth methods.

Author: janko

README.md

@@ -656,6 +656,17 @@ end
 Rails.configuration.middleware.insert_before AnotherMiddleware, Rodauth::Rails::Middleware
 ```
 
+### Skipping Tilt
+
+Rodauth uses the [Tilt] gem to render built-in view & email templates. If you don't want to have Tilt as a dependency, you can disable it, provided that you've imported all view & email templates into your app:
+
+```rb
+# config/initializers/rodauth.rb
+Rodauth::Rails.configure do |config|
+  config.tilt = false # skip loading Tilt gem
+end
+```
+
 ## How it works
 
 ### Rack middleware

lib/generators/rodauth/templates/config/initializers/rodauth.rb.tt

@@ -1,3 +1,5 @@
 Rodauth::Rails.configure do |config|
   config.app = "RodauthApp"
+  # config.middleware = false # disable auto-insertion of Rodauth middleware
+  # config.tilt = false # skip loading Tilt gem for rendering built-in templates
 end

lib/rodauth/rails.rb

@@ -12,9 +12,6 @@ class Error < StandardError
     autoload :Auth, "rodauth/rails/auth"
     autoload :Mailer, "rodauth/rails/mailer"
 
-    @app = nil
-    @middleware = true
-
     class << self
       def lib(**options, &block)
         c = Class.new(Rodauth::Rails::App)
@@ -80,8 +77,13 @@ def configure
         yield self
       end
 
+      @app = nil
+      @middleware = true
+      @tilt = true
+
       attr_writer :app
       attr_writer :middleware
+      attr_writer :tilt
 
       def app
         fail Rodauth::Rails::Error, "app was not configured" unless @app
@@ -92,6 +94,10 @@ def app
       def middleware?
         @middleware
       end
+
+      def tilt?
+        @tilt
+      end
     end
   end
 end

lib/rodauth/rails/app.rb

@@ -9,17 +9,17 @@ class App < Roda
       plugin :hooks
       plugin :pass
 
-      def self.configure(*args, **options, &block)
+      def self.configure(*args, render: Rodauth::Rails.tilt?, **options, &block)
         auth_class = args.shift if args[0].is_a?(Class)
         auth_class ||= Class.new(Rodauth::Rails::Auth)
         name = args.shift if args[0].is_a?(Symbol)
 
         fail ArgumentError, "need to pass optional Rodauth::Auth subclass and optional configuration name" if args.any?
 
         # we'll render Rodauth's built-in view templates within Rails layouts
-        plugin :render, layout: false unless options[:render] == false
+        plugin :render, layout: false unless render == false
 
-        plugin :rodauth, auth_class: auth_class, name: name, csrf: false, flash: false, json: true, **options, &block
+        plugin :rodauth, auth_class: auth_class, name: name, csrf: false, flash: false, json: true, render: render, **options, &block
 
         # we need to do it after request methods from rodauth have been included
         self::RodaRequest.include RequestMethods