add setup foundations: site gate, registration lockdown, coming soon page

- Settings.site_live?/0 and set_site_live/1 for shop visibility control
- Accounts.has_admin?/0 to detect single-tenant admin existence
- Registration lockdown: /users/register redirects when admin exists
- Setup.setup_status/0 aggregates provider, product, and stripe checks
- Coming soon page at /coming-soon with themed styling
- ThemeHook :require_site_live gate on all public shop routes
  - Site live → everyone through
  - Authenticated → admin preview through
  - No admin → fresh install demo through
  - Otherwise → redirect to coming soon
- Go live / take offline toggle on /admin/settings
- 648 tests, 0 failures

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

lib/simpleshop_theme_web/live/admin_live/settings.ex

@@ -6,7 +6,11 @@ defmodule SimpleshopThemeWeb.AdminLive.Settings do
 
   @impl true
   def mount(_params, _session, socket) do
-    {:ok, socket |> assign(:page_title, "Credentials") |> assign_stripe_state()}
+    {:ok,
+     socket
+     |> assign(:page_title, "Settings")
+     |> assign(:site_live, Settings.site_live?())
+     |> assign_stripe_state()}
   end
 
   defp assign_stripe_state(socket) do
@@ -96,6 +100,18 @@ defmodule SimpleshopThemeWeb.AdminLive.Settings do
     end
   end
 
+  def handle_event("toggle_site_live", _params, socket) do
+    new_value = !socket.assigns.site_live
+    {:ok, _} = Settings.set_site_live(new_value)
+
+    message = if new_value, do: "Shop is now live", else: "Shop taken offline"
+
+    {:noreply,
+     socket
+     |> assign(:site_live, new_value)
+     |> put_flash(:info, message)}
+  end
+
   def handle_event("toggle_advanced", _params, socket) do
     {:noreply, assign(socket, :advanced_open, !socket.assigns.advanced_open)}
   end
@@ -106,10 +122,50 @@ defmodule SimpleshopThemeWeb.AdminLive.Settings do
     <Layouts.app flash={@flash} current_scope={@current_scope}>
       <div class="max-w-2xl">
         <.header>
-          Credentials
-          <:subtitle>Connect payment providers and manage API keys</:subtitle>
+          Settings
+          <:subtitle>Shop status, payment providers, and API keys</:subtitle>
         </.header>
 
+        <section class="mt-10">
+          <div class="flex items-center gap-3">
+            <h2 class="text-lg font-semibold">Shop status</h2>
+            <%= if @site_live do %>
+              <span class="inline-flex items-center gap-1 rounded-full bg-green-50 px-2 py-1 text-xs font-medium text-green-700 ring-1 ring-green-600/20 ring-inset">
+                <.icon name="hero-check-circle-mini" class="size-3" /> Live
+              </span>
+            <% else %>
+              <span class="inline-flex items-center gap-1 rounded-full bg-zinc-50 px-2 py-1 text-xs font-medium text-zinc-600 ring-1 ring-zinc-500/10 ring-inset">
+                Offline
+              </span>
+            <% end %>
+          </div>
+          <p class="mt-2 text-sm text-zinc-600">
+            <%= if @site_live do %>
+              Your shop is visible to the public.
+            <% else %>
+              Your shop is offline. Visitors see a "coming soon" page.
+            <% end %>
+          </p>
+          <div class="mt-4">
+            <button
+              phx-click="toggle_site_live"
+              class={[
+                "inline-flex items-center gap-2 rounded-md px-3 py-2 text-sm font-semibold shadow-xs",
+                if(@site_live,
+                  do: "bg-zinc-100 text-zinc-700 hover:bg-zinc-200 ring-1 ring-zinc-300 ring-inset",
+                  else: "bg-green-600 text-white hover:bg-green-500"
+                )
+              ]}
+            >
+              <%= if @site_live do %>
+                <.icon name="hero-eye-slash-mini" class="size-4" /> Take offline
+              <% else %>
+                <.icon name="hero-eye-mini" class="size-4" /> Go live
+              <% end %>
+            </button>
+          </div>
+        </section>
+
         <section class="mt-10">
           <div class="flex items-center gap-3">
             <h2 class="text-lg font-semibold">Stripe</h2>

lib/simpleshop_theme_web/live/shop_live/coming_soon.ex

@@ -0,0 +1,22 @@
+defmodule SimpleshopThemeWeb.ShopLive.ComingSoon do
+  use SimpleshopThemeWeb, :live_view
+
+  @impl true
+  def mount(_params, _session, socket) do
+    {:ok, assign(socket, :page_title, "Coming soon")}
+  end
+
+  @impl true
+  def render(assigns) do
+    ~H"""
+    <main class="flex min-h-screen items-center justify-center px-6 text-center" role="main">
+      <div>
+        <h1 class="text-3xl font-bold tracking-tight sm:text-4xl">{@theme_settings.site_name}</h1>
+        <p class="mt-4 text-lg text-[var(--t-text-muted)]">
+          We're getting things ready. Check back soon.
+        </p>
+      </div>
+    </main>
+    """
+  end
+end

lib/simpleshop_theme_web/live/user_live/registration.ex

@@ -48,9 +48,15 @@ defmodule SimpleshopThemeWeb.UserLive.Registration do
   end
 
   def mount(_params, _session, socket) do
-    changeset = Accounts.change_user_email(%User{}, %{}, validate_unique: false)
-
-    {:ok, assign_form(socket, changeset), temporary_assigns: [form: nil]}
+    if Accounts.has_admin?() do
+      {:ok,
+       socket
+       |> put_flash(:error, "Registration is closed")
+       |> redirect(to: ~p"/users/log-in")}
+    else
+      changeset = Accounts.change_user_email(%User{}, %{}, validate_unique: false)
+      {:ok, assign_form(socket, changeset), temporary_assigns: [form: nil]}
+    end
   end
 
   @impl true