Fix map basemap tiles and add hurricane click-to-map feature

- Replace CARTO basemap tiles (now require API key) with OpenFreeMap
  vector tiles (positron for light, liberty for dark) — no key needed
- Add click handlers on hurricane panel cards to fly to storm on map
- Add flyToHurricane(): switches to map tab, enables hurricane overlay,
  flies to storm coords, shows popup with storm details
- Add /api/hurricanes/track proxy to fetch NHC GIS 5-day forecast track
  line and render it as a dashed overlay on the map

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/server.js

@@ -511,6 +511,23 @@ app.get('/api/hurricanes', async (_req, res) => {
   }
 });
 
+app.get('/api/hurricanes/track', async (req, res) => {
+  const { stormId } = req.query;
+  if (!stormId || !/^[a-z]{2}\d{6}$/i.test(stormId)) {
+    return res.json({ type: 'FeatureCollection', features: [] });
+  }
+  try {
+    const id = stormId.toUpperCase();
+    const r = await fetchWithRetry(
+      `https://www.nhc.noaa.gov/gis/json/${id}_5day_lin.json`,
+      { attempts: 2, timeoutMs: 8000, fetchOptions: { headers: { 'User-Agent': 'weather-app-v2 (nate@necloud.us)', Accept: 'application/json' } } }
+    );
+    res.json(await r.json());
+  } catch {
+    res.json({ type: 'FeatureCollection', features: [] });
+  }
+});
+
 // ── Wildfire perimeter proxy (NIFC) ───────────────────────────────────────────
 const wfCache = { data: null, at: 0 };
 app.get('/api/wildfires', async (_req, res) => {