Account::Sync model and test fixture simplifications (#968)

* Add sync model

* Fresh fixtures for sync tests

* Sync tests overhaul

* Fix entry tests

* Complete remaining model test updates

* Update system tests

* Update demo data task

* Add system tests back to PR checks

* More simplifications, add empty family to fixtures for easier testing

db/migrate/20240707130331_create_account_syncs.rb

@@ -0,0 +1,18 @@
+class CreateAccountSyncs < ActiveRecord::Migration[7.2]
+  def change
+    create_table :account_syncs, id: :uuid do |t|
+      t.references :account, null: false, foreign_key: true, type: :uuid
+      t.string :status, null: false, default: "pending"
+      t.date :start_date
+      t.datetime :last_ran_at
+      t.string :error
+      t.text :warnings, array: true, default: []
+
+      t.timestamps
+    end
+
+    remove_column :accounts, :status, :string
+    remove_column :accounts, :sync_warnings, :jsonb
+    remove_column :accounts, :sync_errors, :jsonb
+  end
+end