Add a year view to the calendar

Pull in @fullcalendar/multimonth so the deadline calendar can show all
twelve months at once, between the month grid and the year list. Events
render as dots there and the type scales down, so the month tables stay
legible two or three to a row.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

site/assets/js/calendar.js

@@ -1,6 +1,7 @@
 import { Calendar } from '@fullcalendar/core'
 import dayGridPlugin from '@fullcalendar/daygrid'
 import listPlugin from '@fullcalendar/list'
+import multiMonthPlugin from '@fullcalendar/multimonth'
 
 document.addEventListener('DOMContentLoaded', function () {
   var el = document.getElementById('pa-calendar')
@@ -10,14 +11,21 @@ document.addEventListener('DOMContentLoaded', function () {
   try { events = JSON.parse(el.dataset.events || '[]') } catch (_) { events = [] }
 
   var cal = new Calendar(el, {
-    plugins: [dayGridPlugin, listPlugin],
+    plugins: [dayGridPlugin, listPlugin, multiMonthPlugin],
     initialView: 'dayGridMonth',
     firstDay: 1,
     events: events,
     headerToolbar: {
       left: 'prev,next today',
       center: 'title',
-      right: 'dayGridMonth,listYear'
+      right: 'dayGridMonth,multiMonthYear,listYear'
+    },
+    views: {
+      multiMonthYear: {
+        // Dots keep the year grid readable when a day holds several deadlines.
+        eventDisplay: 'list-item',
+        multiMonthMinWidth: 260
+      }
     },
     eventClick: function (info) {
       if (info.event.url) {