refactor: Style transaction items for untracked accounts

This commit extends the "Untrack Account" feature by applying a special style to transaction items that belong to an untracked account.

- The transaction item template is modified to apply a "dimmed" style to transactions from untracked accounts.
- The styling follows the precedence: Account (untracked) > Category (muted) > Transaction (hidden).
- The dropdown menu for transaction items now shows "Controlled by account" if the transaction's account is untracked.

app/apps/accounts/urls.py

@@ -31,6 +31,11 @@ urlpatterns = [
         views.account_take_ownership,
         name="account_take_ownership",
     ),
+    path(
+        "account/<int:pk>/toggle-untracked/",
+        views.account_toggle_untracked,
+        name="account_toggle_untracked",
+    ),
     path("account-groups/", views.account_groups_index, name="account_groups_index"),
     path("account-groups/list/", views.account_groups_list, name="account_groups_list"),
     path("account-groups/add/", views.account_group_add, name="account_group_add"),