Add offline model and "new" form/controller

db/migrate/20251029155116_create_offlines.rb

@@ -0,0 +1,10 @@
+class CreateOfflines < ActiveRecord::Migration[8.0]
+  def change
+    create_table :offlines do |t|
+      t.timestamps
+      t.belongs_to :contest, null: false, foreign_key: true
+      t.datetime :start_time, null: false
+      t.datetime :end_time
+    end
+  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_10_28_131431) do
+ActiveRecord::Schema[8.0].define(version: 2025_10_29_155116) do
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -125,6 +125,15 @@ ActiveRecord::Schema[8.0].define(version: 2025_10_28_131431) do
     t.index ["contest_id"], name: "index_messages_on_contest_id"
   end
 
+  create_table "offlines", force: :cascade do |t|
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.integer "contest_id", null: false
+    t.datetime "start_time", null: false
+    t.datetime "end_time"
+    t.index ["contest_id"], name: "index_offlines_on_contest_id"
+  end
+
   create_table "puzzles", force: :cascade do |t|
     t.string "name"
     t.datetime "created_at", null: false
@@ -165,6 +174,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_10_28_131431) do
   add_foreign_key "contestants", "contests"
   add_foreign_key "contests", "users"
   add_foreign_key "messages", "contests"
+  add_foreign_key "offlines", "contests"
   add_foreign_key "puzzles", "contests"
   add_foreign_key "sessions", "users"
 end