update server.js to handle link group name submission

index.html

@@ -31,6 +31,7 @@
     <form id="merge-form">
         <div id="calendars">
             <div class="calendar">
+                <input type="text" id="link-group-name-0" placeholder="Link Group Name">
                 <input type="text" id="prefix-0" placeholder="Prefix">
                 <input type="checkbox" id="override-0">
                 <label for="override-0">Override</label>

script.js

@@ -9,6 +9,7 @@ const form = document.getElementById('merge-form');
             const newCalendar = document.createElement('div');
             newCalendar.className = 'calendar';
             newCalendar.innerHTML = `
+                <input type="text" id="link-group-name-${calendarIndex}" placeholder="Link Group Name">
                 <input type="text" id="prefix-${calendarIndex}" placeholder="Prefix">
                 <input type="checkbox" id="override-${calendarIndex}">
                 <label for="override-${calendarIndex}">Override</label>
@@ -22,6 +23,7 @@ const form = document.getElementById('merge-form');
             event.preventDefault();
             const calendarsData = [];
             for (let i = 0; i < calendarIndex; i++) {
+                const linkGroupName = document.getElementById(`link-group-name-${i}`).value;
                 const prefix = document.getElementById(`prefix-${i}`).value;
                 const override = document.getElementById(`override-${i}`).checked;
                 const url = document.getElementById(`url-${i}`).value;