improve notification accessibility

- use role="status" for info messages, role="alert" for errors
- add aria-live attribute (polite for info, assertive for errors)
- move phx-click to close button for better keyboard navigation
- add close buttons to shop flash messages
- add aria-hidden to decorative icons

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

lib/berrypod_web/components/core_components.ex

@@ -45,8 +45,8 @@ defmodule BerrypodWeb.CoreComponents do
     <div
       :if={msg = render_slot(@inner_block) || Phoenix.Flash.get(@flash, @kind)}
       id={@id}
-      phx-click={JS.push("lv:clear-flash", value: %{key: @kind}) |> hide("##{@id}")}
-      role="alert"
+      role={if(@kind == :error, do: "alert", else: "status")}
+      aria-live={if(@kind == :error, do: "assertive", else: "polite")}
       class="admin-banner"
       {@rest}
     >
@@ -62,7 +62,12 @@ defmodule BerrypodWeb.CoreComponents do
           <p>{msg}</p>
         </div>
         <div class="admin-alert-spacer" />
-        <button type="button" class="admin-alert-close" aria-label={gettext("close")}>
+        <button
+          type="button"
+          class="admin-alert-close"
+          aria-label={gettext("close")}
+          phx-click={JS.push("lv:clear-flash", value: %{key: @kind}) |> hide("##{@id}")}
+        >
           <.icon name="hero-x-mark" class="size-5" />
         </button>
       </div>