Fix workforce sync: split 35-day window into 7-day API chunks

Workforce schedules API enforces a hard 7-day limit per request.
Split the rolling window into up to 5 weekly chunks, fetch each
sequentially, then merge by staff id before pivoting to per-date rows.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/routes/workforce.js

@@ -35,7 +35,27 @@ export async function workforceRoutes(app) {
     const to   = fmtDate(toDate)
 
     try {
-      const staffList = await fetchShifts(from, to, deptIds)
+      // API limit: max 7 days per request — split window into weekly chunks
+      const chunks = []
+      const cur = new Date(fromDate)
+      while (cur <= toDate) {
+        const chunkFrom = fmtDate(cur)
+        const chunkToDate = new Date(cur)
+        chunkToDate.setDate(chunkToDate.getDate() + 6)
+        if (chunkToDate > toDate) chunkToDate.setTime(toDate.getTime())
+        chunks.push({ from: chunkFrom, to: fmtDate(chunkToDate) })
+        cur.setDate(cur.getDate() + 7)
+      }
+
+      const staffMap = {}
+      for (const chunk of chunks) {
+        const chunkStaff = await fetchShifts(chunk.from, chunk.to, deptIds)
+        for (const member of chunkStaff) {
+          if (!staffMap[member.id]) staffMap[member.id] = { id: member.id, name: member.name, days: {} }
+          Object.assign(staffMap[member.id].days, member.days)
+        }
+      }
+      const staffList = Object.values(staffMap)
 
       // Pivot per-member → per-date
       const byDate = {}