feat: add sort by distance and directions to ProductView

- Added sort by distance functionality (same as SearchView)
- Added PharmacyList component with distance display
- Added 'Cómo llegar' button in map popup (Google Maps directions)
- Uses haversineKm for distance calculation

apps/frontend/src/components/PharmacyMap.jsx

@@ -34,6 +34,15 @@ function PharmacyMap({ pharmacies }) {
               <strong>{pharmacy.name}</strong><br />
               {pharmacy.address}
               {pharmacy.phone && <><br />{pharmacy.phone}</>}
+              <br />
+              <a
+                href={`https://www.google.com/maps/dir/?api=1&destination=${pharmacy.latitude},${pharmacy.longitude}`}
+                target="_blank"
+                rel="noopener noreferrer"
+                style={{ color: '#2563eb', marginTop: '8px', display: 'inline-block' }}
+              >
+                📍 Cómo llegar
+              </a>
             </Popup>
           </Marker>
         ))}