Task #692: Auto-scroll bookings day grid to current time (red now-line)

- BookingDayGrid (artifacts/tx-os/src/pages/protocol.tsx) now renders inside
  its own scroll container (max-h-[60vh] overflow-y-auto overscroll-contain).
- New scrollRef + useEffect: when the selected day is today and the now-line
  is within grid hours (showNow), sets scrollTop = nowTop - clientHeight/3
  so the red line sits ~1/3 from the top; otherwise resets scroll to top.
  Effect deps: [dayKey, showNow, scrollSignal] — not re-run on minute ticks,
  so it never fights user scrolling.
- "اليوم" button bumps a todayScrollSignal counter passed as optional
  scrollSignal prop, re-scrolling even when the selected day is already today.
- Removed the previous outer max-h-[70vh] wrapper around BookingDayGrid to
  avoid nested scrollbars.
- No changes to booking block layout, statuses, or list view. RTL-safe
  (logical properties untouched).
- tsc --noEmit clean for tx-os; architect review addressed (60vh per spec).

artifacts/tx-os/src/pages/protocol.tsx

@@ -353,6 +353,7 @@ function BookingDayGrid({
   isAr,
   roomName,
   emptyText,
+  scrollSignal = 0,
 }: {
   bookings: Booking[];
   selectedDay: Date;
@@ -360,6 +361,7 @@ function BookingDayGrid({
   isAr: boolean;
   roomName: (id: number) => string;
   emptyText: string;
+  scrollSignal?: number;
 }) {
   const hours: number[] = [];
   for (let h = GRID_HOUR_START; h <= GRID_HOUR_END; h++) hours.push(h);
@@ -391,6 +393,25 @@ function BookingDayGrid({
       hour12: true,
     }).format(new Date(iso));
 
+  // The grid scrolls inside its own fixed-height container so we can jump
+  // straight to the red "now" line without touching the page scroll. When
+  // the selected day is today, position the line ~1/3 from the top of the
+  // viewport; for other days start at the top.
+  const scrollRef = useRef<HTMLDivElement | null>(null);
+  const dayKey = `${selectedDay.getFullYear()}-${selectedDay.getMonth()}-${selectedDay.getDate()}`;
+  useEffect(() => {
+    const el = scrollRef.current;
+    if (!el) return;
+    if (showNow) {
+      el.scrollTop = Math.max(0, nowTop - el.clientHeight / 3);
+    } else {
+      el.scrollTop = 0;
+    }
+    // Re-run only when the day changes (or the now-line appears/disappears),
+    // not on every minute tick — so we never fight the user's scrolling.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [dayKey, showNow, scrollSignal]);
+
   return (
     <div>
       {dayItems.length === 0 && (
@@ -398,7 +419,11 @@ function BookingDayGrid({
           {emptyText}
         </div>
       )}
-      <div className="flex" style={{ height: gridHeight + 8 }}>
+      <div
+        ref={scrollRef}
+        className="max-h-[60vh] overflow-y-auto overscroll-contain"
+      >
+        <div className="flex" style={{ height: gridHeight + 8 }}>
         <div className="relative w-14 shrink-0" style={{ height: gridHeight }}>
           {hours.map((h) => (
             <div
@@ -474,6 +499,7 @@ function BookingDayGrid({
             </div>
           )}
         </div>
+        </div>
       </div>
     </div>
   );
@@ -628,6 +654,9 @@ export default function ProtocolPage() {
     setSelectedBookings(new Set());
   }, [debouncedBookingSearch, bookingsView, tab]);
   const [selectedDay, setSelectedDay] = useState<Date>(() => new Date());
+  // Bumped by the "اليوم" button to re-scroll the day grid to the now-line
+  // even when the selected day is already today.
+  const [todayScrollSignal, setTodayScrollSignal] = useState(0);
   const [calendarMonth, setCalendarMonth] = useState<Date>(() => new Date());
   const now = useNow(60000);
   const bookedDates = useMemo(() => {
@@ -1444,6 +1473,7 @@ export default function ProtocolPage() {
                           const today = new Date();
                           setSelectedDay(today);
                           setCalendarMonth(today);
+                          setTodayScrollSignal((v) => v + 1);
                         }}
                       >
                         <CalendarDays size={14} className="me-1" />
@@ -1462,16 +1492,15 @@ export default function ProtocolPage() {
                       )}
                     </div>
                   </div>
-                  <div className="max-h-[70vh] overflow-y-auto">
-                    <BookingDayGrid
-                      bookings={bookings.data ?? []}
-                      selectedDay={selectedDay}
-                      now={now}
-                      isAr={isAr}
-                      roomName={roomName}
-                      emptyText={t("protocol.bookings.emptyDay")}
-                    />
-                  </div>
+                  <BookingDayGrid
+                    bookings={bookings.data ?? []}
+                    selectedDay={selectedDay}
+                    now={now}
+                    isAr={isAr}
+                    roomName={roomName}
+                    emptyText={t("protocol.bookings.emptyDay")}
+                    scrollSignal={todayScrollSignal}
+                  />
                 </div>
               </div>
             )}