Add naive impl of seeding alerts

db/migrate/20251008063847_create_alerts.rb

@@ -3,6 +3,7 @@ class CreateAlerts < ActiveRecord::Migration[8.0]
     create_table :alerts do |t|
       t.string :category, null: false
       t.text :description
+      t.string :identifier, null: false
       t.string :park_code, null: false
       t.string :title, null: false
       t.string :url
@@ -11,6 +12,7 @@ class CreateAlerts < ActiveRecord::Migration[8.0]
       t.timestamps
     end
 
+    add_index :alerts, :identifier, unique: true
     add_index :alerts, :park_code
     add_foreign_key :alerts, :parks, column: :park_code, primary_key: :code
   end