Add stale SimpleFin account detection and improve unlink cleanup (#574)

* Add stale account detection and handling in SimpleFin setup

- Introduced UI for managing stale accounts during SimpleFin setup.
- Added logic to detect accounts no longer provided by SimpleFin.
- Implemented actions to delete, move transactions, or skip stale accounts.
- Updated `simplefin_items_controller` with stale account processing and handling.
- Enhanced tests to validate stale account scenarios, including detection, deletion, moving transactions, and skipping.

* Update SimpleFin to SimpleFIN in locale file

Signed-off-by: Juan José Mata <jjmata@jjmata.com>

* Silly changes break things ...

Signed-off-by: Juan José Mata <jjmata@jjmata.com>

* Refactor stale account processing and UI handling

- Moved `target_account.sync_later` to execute after commit for proper recalculation of balances.
- Added additional safeguard in JavaScript to check for `moveRadioTarget` before updating target visibility.

* More silly capitalization changes

* Enhance stale account action handling in SimpleFIN setup

- Introduced `permitted_stale_account_actions` to validate and permit nested `stale_account_actions` parameters.
- Updated `complete_account_setup` to use the new method for safer processing.
- Corrected capitalization in SimpleFIN update success and error messages.

* Add error tracking and UI feedback for stale account actions

- Updated `process_stale_account_actions` to track errors for delete and move actions.
- Enhanced UI to display success and error messages for stale account processing.
- Implemented destruction of conflicting transfers during account move to maintain data integrity.

* Refactor transfer destruction and improve SimpleFIN account setup messages

- Updated `simplefin_items_controller` to use `find_each(&:destroy!)` for transfer deletions, ensuring callbacks are invoked.
- Enhanced localization for success messages in account creation to handle singular and plural cases.

---------

Signed-off-by: Juan José Mata <jjmata@jjmata.com>
Co-authored-by: Josh Waldrep <joshua.waldrep5+github@gmail.com>
Co-authored-by: Juan José Mata <jjmata@jjmata.com>

app/controllers/accounts_controller.rb

@@ -141,11 +141,27 @@ class AccountsController < ApplicationController
 
     begin
       Account.transaction do
+        # Detach holdings from provider links before destroying them
+        provider_link_ids = @account.account_providers.pluck(:id)
+        if provider_link_ids.any?
+          Holding.where(account_provider_id: provider_link_ids).update_all(account_provider_id: nil)
+        end
+
+        # Capture SimplefinAccount before clearing FK (so we can destroy it)
+        simplefin_account_to_destroy = @account.simplefin_account
+
         # Remove new system links (account_providers join table)
         @account.account_providers.destroy_all
 
         # Remove legacy system links (foreign keys)
         @account.update!(plaid_account_id: nil, simplefin_account_id: nil)
+
+        # Destroy the SimplefinAccount record so it doesn't cause stale account issues
+        # This is safe because:
+        # - Account data (transactions, holdings, balances) lives on the Account, not SimplefinAccount
+        # - SimplefinAccount only caches API data which is regenerated on reconnect
+        # - If user reconnects SimpleFin later, a new SimplefinAccount will be created
+        simplefin_account_to_destroy&.destroy!
       end
 
       redirect_to accounts_path, notice: t("accounts.unlink.success")