feat: review open answers in the admin and pick a grader per quiz

- Do oceny admin screen (golem15.quizzes.reviews) over the open answers,
  with a read-only context partial, score and comment virtual fields saved
  through SetScore, confirm and regrade record actions, bulk confirm
- open question type, rubric and max_length in the question form; grader
  dropdown on the quiz form from the grader registry
- Review model with quiz, status and student filters

controllers/quizzes.go

@@ -3,6 +3,7 @@
 package controllers
 
 import (
+	"git.golem15.com/golem15/sm-quizzes-plugin/graders"
 	"git.golem15.com/golem15/sm-quizzes-plugin/models"
 	"git.golem15.com/golem15/summercms/modules/pact"
 )
@@ -11,8 +12,17 @@ var (
 	_ pact.AdminController   = quizzesAdmin{}
 	_ pact.AdminRecordSource = quizzesAdmin{}
 	_ pact.AdminPermissioned = quizzesAdmin{}
+
+	_ pact.DropdownOptionsProvider = quizzesAdmin{}
 )
 
+// GraderOptions lists the grader dropdown choices: the registry golem15.quizzes
+// built at boot. The plugin sets it at Boot; nil offers manual only.
+//
+// TODO: requires SummerCMS change. DropdownOptions receives neither a
+// context nor the app, so the registry comes through a package-level hook.
+var GraderOptions func() []graders.Option
+
 // quizzesAdmin lists and edits quizzes. Questions have their own controller
 // filtered by quiz.
 //
@@ -33,5 +43,25 @@ func (quizzesAdmin) RequiredPermissions() []string {
 	return []string{"golem15.quizzes.access_quizzes"}
 }
 
+// DropdownOptions serves the grader dropdown (options: getGraderOptions):
+// manual, then every grader an activated plugin registered. Other fields
+// have no method-backed options.
+func (quizzesAdmin) DropdownOptions(field string) []pact.Option {
+	if field != "grader" {
+		return nil
+	}
+	opts := []graders.Option{{Code: graders.Manual, Label: graders.ManualLabel}}
+	if GraderOptions != nil {
+		if got := GraderOptions(); len(got) > 0 {
+			opts = got
+		}
+	}
+	out := make([]pact.Option, 0, len(opts))
+	for _, o := range opts {
+		out = append(out, pact.Option{Value: o.Code, Label: o.Label})
+	}
+	return out
+}
+
 // QuizzesController returns the golem15.quizzes.quizzes admin controller.
 func QuizzesController() pact.AdminController { return quizzesAdmin{} }