separate account settings from shop settings

- Create dedicated /admin/account page for user account management
- Move email, password, and 2FA settings from /admin/settings
- Add Account link to top of admin sidebar navigation
- Add TOTP-based two-factor authentication with NimbleTOTP
- Add TOTP verification LiveView for login flow
- Add AccountController for TOTP session management
- Remove Advanced section from settings (duplicated in dev tools)
- Remove user email from sidebar footer (replaced by Account link)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test/berrypod_web/live/admin/layout_test.exs

@@ -37,12 +37,6 @@ defmodule BerrypodWeb.Admin.LayoutTest do
       refute has_element?(view, ~s(a.active[href="/admin/orders"]))
     end
 
-    test "shows user email in sidebar", %{conn: conn, user: user} do
-      {:ok, _view, html} = live(conn, ~p"/admin/orders")
-
-      assert html =~ user.email
-    end
-
     test "shows shop and log out links", %{conn: conn} do
       {:ok, view, _html} = live(conn, ~p"/admin/orders")