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>

lib/berrypod_web/live/admin/dashboard.ex

@@ -154,10 +154,8 @@ defmodule BerrypodWeb.Admin.Dashboard do
   defp launch_checklist(assigns) do
     items = checklist_items(assigns.setup)
 
-    # Email is optional — exclude from progress count
-    required_items = Enum.reject(items, &(&1.key == :email_configured))
-    done_count = Enum.count(required_items, & &1.done)
-    total = length(required_items)
+    done_count = Enum.count(items, & &1.done)
+    total = length(items)
     progress_pct = round(done_count / total * 100)
 
     assigns =
@@ -248,33 +246,36 @@ defmodule BerrypodWeb.Admin.Dashboard do
       %{
         key: :provider_connected,
         label: "Connect a print provider",
-        href: "/admin/providers"
+        href: "/admin/providers?from=checklist"
       },
       %{
         key: :stripe_connected,
         label: "Connect Stripe",
-        href: "/admin/settings"
+        href: "/admin/settings?from=checklist"
       },
       # Post-setup items
       %{
         key: :products_synced,
         label: "Sync your products",
-        href: if(setup.provider_connected, do: "/admin/products", else: "/admin/providers"),
+        href:
+          if(setup.provider_connected,
+            do: "/admin/products?from=checklist",
+            else: "/admin/providers?from=checklist"
+          ),
         hint: "Import products from your print provider."
       },
-      %{
-        key: :theme_customised,
-        label: "Customise your theme",
-        href: "/admin/theme",
-        hint: "Upload your logo, pick your colours, and choose a font that matches your brand."
-      },
       %{
         key: :email_configured,
         label: "Set up email",
-        href: "/admin/settings",
-        optional: true,
+        href: "/admin/settings/email?from=checklist",
         hint: "Needed for order confirmations, abandoned cart emails, and the contact form."
       },
+      %{
+        key: :theme_customised,
+        label: "Customise your theme",
+        href: "/admin/theme?from=checklist",
+        hint: "Upload your logo, pick your colours, and choose a font that matches your brand."
+      },
       %{
         key: :has_orders,
         label: "Place a test order",