Add CORS to API endpoints

src/invidious.cr

@@ -3977,6 +3977,7 @@ public_folder "assets"
 Kemal.config.powered_by_header = false
 add_handler FilteredCompressHandler.new
 add_handler DenyFrame.new
+add_handler APIHandler.new
 add_context_storage_type(User)
 
 Kemal.config.logger = logger

src/invidious/helpers/helpers.cr

@@ -43,6 +43,18 @@ class FilteredCompressHandler < Kemal::Handler
   end
 end
 
+class APIHandler < Kemal::Handler
+  only ["/api/v1/*"]
+
+  def call(env)
+    return call_next env unless only_match? env
+
+    env.response.headers["Access-Control-Allow-Origin"] = "*"
+
+    call_next env
+  end
+end
+
 class DenyFrame < Kemal::Handler
   exclude ["/embed/*"]