fix(i18n): localize Lunchflow account setup (#3330)

Translate the remaining provider-owned setup and status copy while reusing Accountable subtype labels before legacy English fallbacks. Cover German rendering, error handling, and pluralized English and German status summaries.

Co-authored-by: Johns <19662585+Rowdy@users.noreply.github.com>

test/controllers/lunchflow_items_controller_test.rb

@@ -5,6 +5,83 @@ class LunchflowItemsControllerTest < ActionDispatch::IntegrationTest
     sign_in @user = users(:family_admin)
   end
 
+  test "setup accounts renders German subtype options without English fallbacks" do
+    ensure_tailwind_build
+    @user.update!(locale: "de")
+
+    get setup_accounts_lunchflow_item_url(lunchflow_items(:one))
+
+    assert_response :success
+    assert_select "title", text: "Lunch‑Flow-Konten einrichten"
+    assert_select "option", text: "Untertyp auswählen"
+    assert_select "option", text: "Typ auswählen"
+
+    [
+      "Nicht registriertes Anlagekonto",
+      "FHSA (Sparkonto für den ersten Immobilienkauf)",
+      "RDSP (registrierter Sparplan für Menschen mit Behinderung)",
+      "DPSP (aufgeschobener Gewinnbeteiligungsplan)",
+      "PRPP (gemeinschaftlicher registrierter Altersvorsorgeplan)",
+      "LIF (lebenslanger Einkommensfonds)",
+      "LRIF (gebundener Altersvorsorge-Einkommensfonds)",
+      "PRIF (vorgeschriebener registrierter Altersvorsorge-Einkommensfonds)",
+      "RLIF (beschränkter lebenslanger Einkommensfonds)",
+      "Assurance Vie",
+      "Eigenheimkredit",
+      "Kreditlinie",
+      "Unternehmenskredit"
+    ].each do |label|
+      assert_select "option", text: label
+    end
+
+    assert_select "option", text: "UGMA-Treuhandkonto"
+
+    refute_includes response.body, "Select subtype"
+    refute_includes response.body, "Select type"
+    refute_includes response.body, "First Home Savings Account"
+    refute_includes response.body, "UGMA Custodial Account"
+  end
+
+  test "setup accounts preserves the English title and placeholders" do
+    ensure_tailwind_build
+    @user.update!(locale: "en")
+
+    get setup_accounts_lunchflow_item_url(lunchflow_items(:one))
+
+    assert_response :success
+    assert_select "title", text: "Set Up Lunch Flow Accounts"
+    assert_select "option", text: "Select subtype"
+    assert_select "option", text: "Select type"
+  end
+
+  test "account setup localizes an unexpected error in German" do
+    @user.update!(locale: "de")
+    lunchflow_account = lunchflow_accounts(:investment_account)
+    Account.stubs(:create_and_sync).raises(StandardError, "Synthetic failure")
+
+    post complete_account_setup_lunchflow_item_url(lunchflow_items(:one)), params: {
+      account_types: { lunchflow_account.id => "Investment" },
+      account_subtypes: { lunchflow_account.id => "brokerage" }
+    }
+
+    assert_redirected_to accounts_path
+    assert_equal "Konten konnten nicht angelegt werden: Ein unerwarteter Fehler ist aufgetreten. Versuch es noch einmal.", flash[:alert]
+  end
+
+  test "account setup preserves the unexpected error in English" do
+    @user.update!(locale: "en")
+    lunchflow_account = lunchflow_accounts(:investment_account)
+    Account.stubs(:create_and_sync).raises(StandardError, "Synthetic failure")
+
+    post complete_account_setup_lunchflow_item_url(lunchflow_items(:one)), params: {
+      account_types: { lunchflow_account.id => "Investment" },
+      account_subtypes: { lunchflow_account.id => "brokerage" }
+    }
+
+    assert_redirected_to accounts_path
+    assert_equal "Failed to create accounts: An unexpected error occurred", flash[:alert]
+  end
+
   test "invalid non-Turbo create redirects instead of rendering a missing template" do
     assert_no_difference "LunchflowItem.count" do
       post lunchflow_items_url, params: {