webui: fix relative timestamps (seconds, not milliseconds)

f.date/f.ago assumed JS milliseconds, but the backend emits Unix epoch
seconds everywhere (created_at, feed lastUpdate, rule lastMatch, …), so
every real timestamp rendered as ~20607 days ago (now - ~1.78e9 ms).
Treat the formatter input as seconds. Search results show the indexer's
pubDate string directly rather than mis-parsing it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/js/app.js

@@ -1426,7 +1426,7 @@ function searchTable(rows) {
     ${rows.map((r, i) => `<tr>
       <td>${f.esc(r.name)}</td><td class="num">${f.bytes(r.size)}</td>
       <td class="num" style="color:var(--up)">${r.seeds}</td><td class="num dim">${r.leeches}</td>
-      <td class="dim">${f.esc(r.engine)}</td><td class="num dim">${f.ago(r.pubDate)}</td>
+      <td class="dim">${f.esc(r.engine)}</td><td class="num dim">${r.pubDate ? f.esc(r.pubDate) : '–'}</td>
       <td><button class="btn" data-sr="${i}">＋ Add</button></td></tr>`).join('')}
   </tbody></table>`;
 }