Add audience to token claims and optimize response

Includes an "aud" claim to access tokens for improved validation and configuration of a default audience URL in the settings. Changes `context.response.write` to `context.response.print` for efficiency in response handling. These adjustments enhance security and performance consistency across the system.

src/authly/access_token.cr

@@ -38,6 +38,7 @@ module Authly
         "exp"   => ACCESS_TTL.from_now.to_unix,
         "scope" => @scope,
         "jti"   => @jti, # Include the jti in the token claims
+        "aud"   => Authly.config.audience,
       })
     end
 

src/authly/configuration.cr

@@ -12,5 +12,6 @@ module Authly
     property algorithm : JWT::Algorithm = JWT::Algorithm::HS256
     property token_strategy : Symbol = :jwt
     property state_store : StateStore = InMemoryStateStore.new
+    property audience : String = "https://your-domain.com/oauth/token"
   end
 end

src/authly/handlers/response_helper.cr

@@ -3,7 +3,7 @@ module Authly
     def self.write(context, status_code, content_type = "text/plain", body = "")
       context.response.status_code = status_code
       context.response.content_type = content_type
-      context.response.write body
+      context.response.print body
     end
 
     def self.redirect(context, location)