feat: add test mode to quizzes and withhold its solutions

- mode, navigation and max_attempts columns with Go-side defaults
- classes.Withheld gates every solution field of the answer feedback
  and the attempt result while a test attempt is open
- a test's quiz detail lists no questions before the attempt starts
- admin fields and lang keys for the three settings

updates/20261109120000_add_test_mode_to_quizzes.go

@@ -0,0 +1,28 @@
+// Code generated by summer make. DO NOT EDIT.
+
+package updates
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// AddTestModeToQuizzes returns the 20261109120000_add_test_mode_to_quizzes gormigrate entry.
+// A test quiz withholds solutions until the attempt is finished; navigation
+// and max_attempts apply only to tests. Every existing quiz stays a learning
+// quiz with free navigation and no attempt limit.
+func AddTestModeToQuizzes() *gormigrate.Migration {
+	return &gormigrate.Migration{
+		ID: "20261109120000_add_test_mode_to_quizzes",
+		Migrate: func(tx *gorm.DB) error {
+			return tx.Exec(`ALTER TABLE golem15_quizzes_quizzes
+    ADD COLUMN mode VARCHAR(20) NOT NULL DEFAULT 'learning' CHECK (mode IN ('learning', 'test')),
+    ADD COLUMN navigation VARCHAR(20) NOT NULL DEFAULT 'free' CHECK (navigation IN ('free', 'one_way')),
+    ADD COLUMN max_attempts INTEGER NULL CHECK (max_attempts IS NULL OR max_attempts >= 1)`).Error
+		},
+		Rollback: func(tx *gorm.DB) error {
+			return tx.Exec(`ALTER TABLE golem15_quizzes_quizzes
+    DROP COLUMN IF EXISTS max_attempts, DROP COLUMN IF EXISTS navigation, DROP COLUMN IF EXISTS mode`).Error
+		},
+	}
+}