refactor: generatePlan returns {assignments, skippedDates}

js/algorithm.js

@@ -76,9 +76,10 @@ function scoreCandidate(employee, isoDate, allHistory, randomFn) {
   return score;
 }
 
-// Returns [{ date, employeeId, manual: false }] for each assigned workday
+// Returns { assignments: [{ date, employeeId, manual: false }], skippedDates: [] }
 export function generatePlan(workdays, employees, history, randomFn = Math.random) {
   const monthAssignments = [];
+  const skippedDates = [];
 
   for (const date of workdays) {
     const candidates = employees.filter(e =>
@@ -93,5 +94,5 @@ export function generatePlan(workdays, employees, history, randomFn = Math.rando
     monthAssignments.push({ date, employeeId: scored[0].employee.id, manual: false });
   }
 
-  return monthAssignments;
+  return { assignments: monthAssignments, skippedDates };
 }