Fix transfer share links and redesign recipient download email.

Use transfer.ladill.com share URLs in notifications and APIs, add the email
logo, and show file details with a prominent download button.

Co-authored-by: Cursor <cursoragent@cursor.com>

resources/views/mail/notifications/layout.blade.php

@@ -367,7 +367,11 @@
                     <div class="email-container">
                         {{-- Header with Logo --}}
                         <div class="email-header">
-                            <img src="{{ config('app.url') }}/images/logo/ladill-logo-white.png" alt="Ladill" class="email-logo">
+                            @hasSection('email-header')
+                                @yield('email-header')
+                            @else
+                                <img src="{{ config('app.url') }}/images/logo/ladill-logo-white.png" alt="Ladill" class="email-logo">
+                            @endif
                         </div>
 
                         @hasSection('icon-header')