Improve onboarding: redirect to site page after creation

- After creating a site, redirect to site detail page instead of list
- Show helpful empty state on site page with instructions to add equipment
- Flash message guides user to add their first device

lib/towerops_web/live/site_live/form.ex

@@ -63,11 +63,11 @@ defmodule ToweropsWeb.SiteLive.Form do
     site_params = Map.put(site_params, "organization_id", socket.assigns.organization.id)
 
     case Sites.create_site(site_params) do
-      {:ok, _site} ->
+      {:ok, site} ->
         {:noreply,
          socket
-         |> put_flash(:info, "Site created successfully")
-         |> push_navigate(to: ~p"/orgs/#{socket.assigns.organization.slug}/sites")}
+         |> put_flash(:info, "Site created successfully! Now add your first device.")
+         |> push_navigate(to: ~p"/orgs/#{socket.assigns.organization.slug}/sites/#{site.id}")}
 
       {:error, %Ecto.Changeset{} = changeset} ->
         {:noreply, assign(socket, :form, to_form(changeset))}

lib/towerops_web/live/site_live/show.html.heex

@@ -80,7 +80,26 @@
       </div>
 
       <%= if @equipment == [] do %>
-        <p class="text-sm text-zinc-600 dark:text-zinc-400">No equipment at this site yet.</p>
+        <div class="rounded-lg border-2 border-dashed border-zinc-300 bg-zinc-50 p-8 text-center dark:border-zinc-700 dark:bg-zinc-900">
+          <.icon name="hero-server" class="mx-auto h-12 w-12 text-zinc-400 dark:text-zinc-600" />
+          <h4 class="mt-4 text-base font-semibold text-zinc-900 dark:text-zinc-100">
+            Add your first device
+          </h4>
+          <p class="mt-2 text-sm text-zinc-600 dark:text-zinc-400">
+            Start monitoring by adding network equipment to this site.
+          </p>
+          <p class="mt-1 text-sm text-zinc-600 dark:text-zinc-400">
+            You can add routers, switches, servers, or any device with an IP address.
+          </p>
+          <div class="mt-6">
+            <.button
+              navigate={~p"/orgs/#{@current_organization.slug}/equipment/new?site_id=#{@site.id}"}
+              variant="primary"
+            >
+              <.icon name="hero-plus" class="h-5 w-5" /> Add Equipment
+            </.button>
+          </div>
+        </div>
       <% else %>
         <div class="space-y-3">
           <div