feat(inbox): RecoveryToast for ≥7-day gap reentry

Task 28 of the slice plan. Renders the green '🌱 흐름을 다시
이어갑니다' banner only when the parent says show=true
(continuity.showRecoveryToast && !dismissedToday). Click ✕
calls onDismiss which persists today's date in localStorage
via recoveryToast.ts, suppressing it for the rest of the KST
day even after a reload.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/renderer/inbox/components/RecoveryToast.tsx

@@ -1,2 +1,16 @@
 import React from 'react';
-export function RecoveryToast(_: { show: boolean; onDismiss: () => void }) { return null; }
+
+interface Props {
+  show: boolean;
+  onDismiss: () => void;
+}
+
+export function RecoveryToast({ show, onDismiss }: Props): React.ReactElement | null {
+  if (!show) return null;
+  return (
+    <div className="banner recovery">
+      <span>🌱 흐름을 다시 이어갑니다</span>
+      <button onClick={onDismiss} aria-label="닫기">✕</button>
+    </div>
+  );
+}