fix(calendar): use dynamic year range instead of hardcoded 2026 (#1)

currentYear now initializes to the current year and the year selector
offers a rolling range (this year -1 to +2) so plans can be created
for years other than 2026.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

js/calendar.js

@@ -7,7 +7,7 @@ const MONTHS = ['Januar','Februar','März','April','Mai','Juni',
   'Juli','August','September','Oktober','November','Dezember'];
 const WD_LABELS = ['Mo','Di','Mi','Do','Fr','Sa','So'];
 
-let currentYear = 2026;
+let currentYear = new Date().getFullYear();
 let currentMonth = Math.min(Math.max(new Date().getMonth() + 1, 1), 12);
 let currentPlan = []; // [{ date, employeeId, manual }] for displayed month
 
@@ -41,11 +41,14 @@ export function renderCalendar() {
   yearLabel.textContent = 'Jahr:';
 
   const yearSel = document.createElement('select');
-  const yearOpt = document.createElement('option');
+  const thisYear = new Date().getFullYear();
-  yearOpt.value = '2026';
+  for (let y = thisYear - 1; y <= thisYear + 2; y++) {
-  yearOpt.textContent = '2026';
+    const opt = document.createElement('option');
-  yearOpt.selected = true;
+    opt.value = String(y);
-  yearSel.appendChild(yearOpt);
+    opt.textContent = String(y);
+    if (y === currentYear) opt.selected = true;
+    yearSel.appendChild(opt);
+  }
 
   const slotsLabel = document.createElement('label');
   slotsLabel.textContent = 'Pro Tag:';