feat(view): one top row for the status and backup, transient results as toasts

The status line and the backup banner share one row (the banner appears only when a backup exists). Results and notices
show as toasts that close after 4 s; problems stay until closed. The status line keeps only the empty-state hint.

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

src/style.css

@@ -722,3 +722,15 @@ body { background: #eef1f4; font-family: 'Noto Sans KR', system-ui, sans-serif;
   #view-quantity .piers, #quantity-export, #quantity-print { display: none !important; }
   .quantity .rebar-table { font-size: 10px; }
 }
+
+/* 상단: 상태 줄과 백업 배너를 한 줄에 (승인 2026-10-23) */
+.status-row { display: flex; align-items: center; flex-wrap: wrap; gap: 4px 12px; padding: 4px 16px; }
+.status-row .status-line { padding: 0; margin: 0; }
+.backup-inline { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; font-size: 13px; color: var(--muted); }
+.backup-inline .btn.small { min-height: 44px; }
+
+/* 알림 토스트: 일반 메시지는 4초 뒤 사라지고, 오류는 닫을 때까지 남음 */
+.toast-host { position: fixed; right: 16px; bottom: 16px; display: flex; flex-direction: column; gap: 8px; z-index: 50; max-width: min(360px, calc(100vw - 32px)); }
+.toast { display: flex; align-items: center; gap: 10px; background: #1b2733; color: #ffffff; padding: 10px 14px; border-radius: 6px; font-size: 13px; box-shadow: 0 4px 14px rgba(0, 0, 0, 0.2); }
+.toast.error { background: #8a1c1c; }
+.toast .btn { min-height: 44px; }