Squash device migrations into single table creation

Consolidates the session reference and index cleanup into the original
CreateActionPushNativeDevices migration for a cleaner migration history.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

db/migrate/20260114203313_create_action_push_native_devices.rb

@@ -4,7 +4,8 @@ class CreateActionPushNativeDevices < ActiveRecord::Migration[8.0]
       t.string :name
       t.string :platform, null: false
       t.string :token, null: false
-      t.belongs_to :owner, polymorphic: true, type: :uuid
+      t.belongs_to :owner, polymorphic: true, type: :uuid, index: false
+      t.belongs_to :session, type: :uuid, foreign_key: true
 
       t.timestamps
     end

db/migrate/20260121184815_add_session_to_action_push_native_devices.rb

@@ -1,5 +0,0 @@
-class AddSessionToActionPushNativeDevices < ActiveRecord::Migration[8.2]
-  def change
-    add_reference :action_push_native_devices, :session, foreign_key: true, type: :uuid
-  end
-end

db/migrate/20260121194404_remove_redundant_owner_index_from_action_push_native_devices.rb

@@ -1,5 +0,0 @@
-class RemoveRedundantOwnerIndexFromActionPushNativeDevices < ActiveRecord::Migration[8.2]
-  def change
-    remove_index :action_push_native_devices, column: [ :owner_type, :owner_id ]
-  end
-end