Unify primary buttons with gradient pill design across Ladill Mini.

Add shared btn-primary components and plus icons on create/new actions for a consistent Ladill UI.

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

resources/views/email/mailboxes/create.blade.php

@@ -86,8 +86,10 @@
                 </div>
                 @error('password')<p class="text-xs text-rose-600">{{ $message }}</p>@enderror
 
-                <button class="w-full rounded-xl bg-indigo-600 px-4 py-3 text-sm font-semibold text-white hover:bg-indigo-700"
-                        x-text="free ? 'Create free mailbox' : ('Create mailbox — ' + fmt(price) + '/mo')">Create mailbox</button>
+                <button class="btn-primary w-full btn-primary-lg">
+                    <svg class="h-4 w-4 shrink-0" fill="none" stroke="currentColor" stroke-width="2" viewBox="0 0 24 24" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 4.5v15m7.5-7.5h-15"/></svg>
+                    <span x-text="free ? 'Create free mailbox' : ('Create mailbox — ' + fmt(price) + '/mo')">Create mailbox</span>
+                </button>
             </form>
         </div>
     @endif