improve setup UX: password field, setup hook, checklist banners, theme tweaks

- add password field and required shop name to setup wizard
- extract SetupHook for DRY redirect to /setup when no admin exists
- add ?from=checklist param to checklist hrefs with contextual banner on
  email settings and theme pages for easy return to dashboard
- remove email warning banner from admin layout (checklist covers it)
- make email a required checklist item (no longer optional)
- add DevReset module for wiping dev data without restart
- rename "Theme Studio" to "Theme", drop subtitle
- lower theme editor side-by-side breakpoint from 64em to 48em
- clean up login/registration pages (remove dead registration_open code)
- fix settings.put_secret to invalidate cache after write

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/berrypod_web/live/auth/login_test.exs

@@ -8,6 +8,7 @@ defmodule BerrypodWeb.Auth.LoginTest do
 
   describe "login page" do
     setup do
+      user_fixture()
       Mailer.mark_email_verified()
       :ok
     end
@@ -16,7 +17,6 @@ defmodule BerrypodWeb.Auth.LoginTest do
       {:ok, _lv, html} = live(conn, ~p"/users/log-in")
 
       assert html =~ "Log in"
-      assert html =~ "Set up your shop"
       assert html =~ "Log in with email"
     end
   end
@@ -44,6 +44,8 @@ defmodule BerrypodWeb.Auth.LoginTest do
     end
 
     test "does not disclose if user is registered", %{conn: conn} do
+      user_fixture()
+
       {:ok, lv, _html} = live(conn, ~p"/users/log-in")
 
       {:ok, _lv, html} =
@@ -74,6 +76,8 @@ defmodule BerrypodWeb.Auth.LoginTest do
     test "redirects to login page with a flash error if credentials are invalid", %{
       conn: conn
     } do
+      user_fixture()
+
       {:ok, lv, _html} = live(conn, ~p"/users/log-in")
 
       form =
@@ -107,6 +111,9 @@ defmodule BerrypodWeb.Auth.LoginTest do
 
   describe "email configured and verified" do
     setup do
+      # Create user before switching adapter (fixture sends a confirmation email)
+      _user = user_fixture()
+
       original = Application.get_env(:berrypod, Berrypod.Mailer)
 
       Application.put_env(:berrypod, Berrypod.Mailer,
@@ -154,17 +161,9 @@ defmodule BerrypodWeb.Auth.LoginTest do
     end
   end
 
-  describe "login navigation" do
-    test "redirects to setup page when the setup link is clicked", %{conn: conn} do
-      {:ok, lv, _html} = live(conn, ~p"/users/log-in")
-
-      {:ok, _setup_live, setup_html} =
-        lv
-        |> element("main a", "Set up your shop")
-        |> render_click()
-        |> follow_redirect(conn, ~p"/setup")
-
-      assert setup_html =~ "Set up your shop"
+  describe "no admin exists" do
+    test "redirects to setup", %{conn: conn} do
+      assert {:error, {:redirect, %{to: "/setup"}}} = live(conn, ~p"/users/log-in")
     end
   end