Magnet link handler (#15)

* feat: Magnet link handler registration on the config page

pkg/qbit/server/templates/download.html

@@ -69,6 +69,19 @@
                     submitBtn.innerHTML = originalText;
                 }
             });
+
+            // Read the URL parameters for a magnet link and add it to the download queue if found
+            const urlParams = new URLSearchParams(window.location.search);
+            const magnetURI = urlParams.get('magnet');
+            if (magnetURI) {
+                document.getElementById('magnetURI').value = magnetURI;
+                try {
+                    document.getElementById('submitDownload').click();
+                    history.replaceState({}, document.title, window.location.pathname);
+                } catch (error) {
+                    console.error('Error adding download:', error);
+                }
+            }
         });
     </script>
 {{ end }}