fix(admin-invites): increase create form gap, align edit buttons bottom with select

app/templates/admin_invites.html

@@ -15,7 +15,7 @@
 <!-- Add new code -->
 <div style="margin-bottom:2rem;padding:1.5rem;background:var(--card-bg);border-radius:var(--radius);border:1px solid var(--border)">
     <h3 style="margin-bottom:1rem;font-size:1rem">创建邀请码</h3>
-    <form method="post" action="/admin/invites/add" class="admin-invite-form" style="flex-direction:column;gap:.85rem">
+    <form method="post" action="/admin/invites/add" class="admin-invite-form" style="flex-direction:column;gap:1.1rem">
         <div class="aif-row">
             <label class="aif-label">邀请码（留空自动生成）</label>
             <input type="text" name="code" maxlength="8" placeholder="自动生成" class="aif-input" style="text-transform:uppercase">