calendar: anchor week to current IST day on load

src/components/variants/Calendar.tsx

@@ -129,8 +129,9 @@ export function CalendarView() {
         if (cancelled) return;
         setDrives(td);
         setCars((c.records as unknown as Car[]) ?? []);
+        const todayKey = istDayKey(new Date().toISOString());
         const days = td.map((r) => istDayKey(r.slot_start)).sort();
-        setWeekStart(days[0] ?? null);
+        setWeekStart(days.length ? todayKey : null);
       })
       .catch((e: any) => !cancelled && setError(e?.message ?? "Failed to load"))
       .finally(() => !cancelled && setLoading(false));