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/templates/accounts/fragments/list.html

@@ -71,6 +71,19 @@
                  hx-get="{% url 'account_share_settings' pk=account.id %}">
                 <i class="fa-solid fa-share fa-fw"></i></a>
                 {% endif %}
+                <a class="btn btn-secondary btn-sm"
+                   role="button"
+                   hx-post="{% url 'account_toggle_untracked' pk=account.id %}"
+                   hx-trigger='updated from:body'
+                   hx-swap="none"
+                   data-bs-toggle="tooltip"
+                   data-bs-title="{% if account.is_untracked_by user %}{% translate "Track" %}{% else %}{% translate "Untrack" %}{% endif %}">
+                  {% if account.is_untracked_by user %}
+                    <i class="fa-solid fa-eye-slash fa-fw"></i>
+                  {% else %}
+                    <i class="fa-solid fa-eye fa-fw"></i>
+                  {% endif %}
+                </a>
               </div>
             </td>
             <td class="col">{{ account.name }}</td>