Add contest duration & complete ranking mode implementation

db/migrate/20251118074900_add_duration_to_contest.rb

@@ -0,0 +1,5 @@
+class AddDurationToContest < ActiveRecord::Migration[8.0]
+  def change
+    add_column :contests, :duration, :string
+  end
+end

db/migrate/20251118074914_add_duration_seconds_to_contest.rb

@@ -0,0 +1,5 @@
+class AddDurationSecondsToContest < ActiveRecord::Migration[8.0]
+  def change
+    add_column :contests, :duration_seconds, :integer
+  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_14_093213) do
+ActiveRecord::Schema[8.0].define(version: 2025_11_18_074914) do
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -98,6 +98,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_11_14_093213) do
     t.boolean "public", default: false
     t.boolean "offline_form", default: false
     t.string "ranking_mode"
+    t.string "duration"
+    t.integer "duration_seconds"
     t.index ["slug"], name: "index_contests_on_slug", unique: true
     t.index ["user_id"], name: "index_contests_on_user_id"
   end