Add hidden setting to puzzles

#19

db/migrate/20251204100550_add_hidden_to_puzzle.rb

@@ -0,0 +1,5 @@
+class AddHiddenToPuzzle < ActiveRecord::Migration[8.0]
+  def change
+    add_column :puzzles, :hidden, :boolean
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_11_20_152211) do
+ActiveRecord::Schema[8.0].define(version: 2025_12_04_100550) do
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -161,6 +161,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_20_152211) do
     t.integer "contest_id", null: false
     t.string "brand"
     t.integer "pieces", null: false
+    t.boolean "hidden"
     t.index ["contest_id"], name: "index_puzzles_on_contest_id"
   end