Show Reddit post age in conversations

tests/dashboard/conversations.test.tsx

@@ -49,6 +49,7 @@ function detailFixture(chat = alice) {
       title: 'Looking for a chat',
       url: 'https://reddit.com/r/casualconversation/comments/post-1',
       imageUrl: 'https://i.redd.it/source-post.jpg',
+      postedAt: Date.now() - (2 * 60 * 60 * 1000),
       sentAt: 1_785_999_800_000,
     },
     automation: { turnsUsed: 0, remainingTurns: 3, status: 'active', handoffReason: null },
@@ -142,6 +143,7 @@ describe('ConversationsPage', () => {
       'src',
       'https://i.redd.it/source-post.jpg',
     );
+    expect(screen.getByText('2h ago')).toBeInTheDocument();
     expect(screen.getByRole('img', { name: 'Source post: Looking for a chat' })).toHaveClass('is-blurred');
     await user.click(screen.getByRole('button', { name: 'Reveal original image' }));
     expect(screen.getByRole('img', { name: 'Source post: Looking for a chat' })).not.toHaveClass('is-blurred');