fix: reuse account modal surface for deletion (#23)

frontend/src/app/globals.css

@@ -707,8 +707,5 @@ input:disabled, select:disabled { color: var(--color-ink-tertiary); background:
   .auth-panel h1 { font-size: var(--type-display-sm); }
   .admin-section { padding: var(--space-5); }
 }
-.session-delete-overlay { position: fixed; inset: 0; z-index: 100; display: grid; place-items: center; padding: var(--space-5); background: rgb(0 0 0 / 32%); }
-.session-delete-confirmation { width: min(420px, 100%); padding: var(--space-6); border: 1px solid var(--border); border-radius: 8px; background: var(--background); box-shadow: 0 20px 56px rgb(0 0 0 / 24%); }
-.session-delete-confirmation h2 { margin: 0 0 var(--space-3); font-size: var(--type-title-lg); }
-.session-delete-confirmation p { margin: 0; color: var(--muted-foreground); }
-.session-delete-actions { display: flex; justify-content: flex-end; gap: var(--space-3); margin-top: var(--space-6); }
+.session-delete-overlay { z-index: 100; }
+.session-delete-confirmation p { margin: 0; color: var(--color-ink-secondary); }

frontend/src/app/page.tsx

@@ -2324,11 +2324,11 @@ export default function Home() {
           onOpenLogout={() => openAccountDialog("logout")}
         />
         {pendingSessionDeletion ? (
-          <div className="session-delete-overlay" role="presentation" onMouseDown={() => setPendingSessionDeletion(null)}>
-            <section className="session-delete-confirmation" role="alertdialog" aria-modal="true" aria-label="确认删除聊天记录" onMouseDown={(event) => event.stopPropagation()}>
+          <div className="account-modal-overlay session-delete-overlay" role="presentation" onMouseDown={() => setPendingSessionDeletion(null)}>
+            <section className="account-modal logout-modal session-delete-confirmation" role="alertdialog" aria-modal="true" aria-label="确认删除聊天记录" onMouseDown={(event) => event.stopPropagation()}>
               <h2>删除聊天记录？</h2>
               <p>“{pendingSessionDeletion.title}”将被永久删除，无法恢复。</p>
-              <div className="session-delete-actions">
+              <div className="dialog-actions">
                 <button type="button" onClick={() => setPendingSessionDeletion(null)}>取消</button>
                 <button className="danger-button" type="button" onClick={() => {
                   const session = pendingSessionDeletion;