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

lang/en/lang.yaml

@@ -51,6 +51,8 @@ quizzes:
     navigation_comment: Applies to tests only.
     max_attempts: Attempt limit
     max_attempts_comment: Tests only. Leave empty for no limit.
+    grader: Grading of open questions
+    grader_comment: "Manual: you grade every answer yourself. Installed plugins add other options."
 questions:
     title: Questions
     question: Question
@@ -59,11 +61,16 @@ questions:
     type: Type
     type_single: Single choice
     type_multiple: Multiple choice
+    type_open: Open question
     type_self_check: Self-check (flashcard)
     category: Category
     points: Points
     answer_text: Model answer
-    answer_text_comment: Revealed for self-check questions.
+    answer_text_comment: Revealed for self-check questions. For an open question it is the model answer.
+    rubric: Grading criteria (for the grader only)
+    rubric_comment: Only the grader sees it, never the student. Applies to open questions.
+    max_length: Max. answer length
+    max_length_comment: Characters; empty means 2000. Applies to open questions.
     explanation: Explanation
 answers:
     title: Answers
@@ -81,3 +88,45 @@ attempts:
     score_points: Points
     max_points: Max points
     score_percent: Score (%)
+reviews:
+    title: To review
+    answer: Open answer
+    context: Answer
+    quiz: Quiz
+    question: Question
+    student: Student
+    text: Student's answer
+    max_length: Character limit
+    status: Status
+    status_pending: waiting for a grade
+    status_graded: to be verified
+    status_failed: grading failed
+    status_reviewed: verified
+    grader: Grader
+    grader_points: Grader's points
+    grader_feedback: Grader's feedback
+    grading_error: Grading error
+    grading_attempts: Grading attempts
+    points: Points
+    points_short: pts
+    graded_at: Graded
+    reviewed_at: Verified
+    model_answer: Model answer
+    rubric: Grading criteria
+    review_points: Points (final)
+    review_points_comment: From 0 to the question's points, in steps of 0.5.
+    review_comment: Comment to the student
+    review_comment_comment: The student sees it with their answer. Saving points replaces an earlier comment.
+    confirm: Confirm the grade
+    confirm_selected: Confirm selected
+    confirmed: Grade confirmed.
+    regrade: Grade again
+    regrade_confirm: The answer goes back to grading and loses the grader's current result.
+    regraded: The answer was sent to be graded again.
+    points_required: Enter the points to save a grade.
+    points_invalid: Points must be from 0 to the question's points, in steps of 0.5.
+    no_grader_score: This answer has no grader's score yet; enter the points yourself.
+    already_reviewed: This answer is already verified.
+    grader_manual: This quiz is graded manually; nothing can grade the answer again.
+    not_found: This answer was not found.
+    not_created: Open answers come from students; they cannot be added or deleted here.