feat: improve email copy UX with colored alerts and mailto button

- Green success alert for copied confirmation
- Blue info alert with BCC privacy tip
- Mailto button opens email program with BCC recipients
- Alerts stack vertically instead of overlapping

lib/mv_web/live/member_live/index.ex

@@ -146,7 +146,7 @@ defmodule MvWeb.MemberLive.Index do
           socket
           |> push_event("copy_to_clipboard", %{text: email_string})
           |> put_flash(
-            :info,
+            :success,
             ngettext(
               "Copied %{count} email address to clipboard",
               "Copied %{count} email addresses to clipboard",
@@ -154,6 +154,10 @@ defmodule MvWeb.MemberLive.Index do
               count: email_count
             )
           )
+          |> put_flash(
+            :warning,
+            gettext("Tip: Paste email addresses into the BCC field for privacy compliance")
+          )
 
         {:noreply, socket}
       end