fix: restrict today highlight to date header only

Remove today background/border from data row cells so the yellow
highlight only appears on the day label, not the entire column.

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

components/WeekCalendar.tsx

@@ -30,11 +30,9 @@ function parseDate(iso: string) {
 
 function DayCell({
   dayData,
-  isToday,
   isWeekend,
 }: {
   dayData: DayData | undefined;
-  isToday: boolean;
   isWeekend: boolean;
 }) {
   const base: React.CSSProperties = {
@@ -44,14 +42,7 @@ function DayCell({
     borderBottom: "1px solid var(--color-border)",
     borderLeft: "1px solid var(--color-border)",
     height: 56,
-    background: isToday
-      ? "var(--color-today-bg)"
-      : isWeekend
-      ? "var(--color-weekend-header)"
-      : "transparent",
-    borderLeftColor: isToday ? "var(--color-today-border)" : undefined,
-    borderRightColor: isToday ? "var(--color-today-border)" : undefined,
-    borderRight: isToday ? "1px solid var(--color-today-border)" : undefined,
+    background: isWeekend ? "var(--color-weekend-header)" : "transparent",
     transition: "background 120ms ease",
   };
 
@@ -172,14 +163,12 @@ function ParkRow({
   weekDates,
   parsedDates,
   parkData,
-  today,
 }: {
   park: Park;
   parkIdx: number;
   weekDates: string[];
   parsedDates: ReturnType<typeof parseDate>[];
   parkData: Record<string, DayData>;
-  today: string;
 }) {
   const rowBg = parkIdx % 2 === 0 ? "var(--color-bg)" : "var(--color-surface)";
   return (
@@ -214,7 +203,6 @@ function ParkRow({
         <DayCell
           key={date}
           dayData={parkData[date]}
-          isToday={date === today}
           isWeekend={parsedDates[i].isWeekend}
         />
       ))}
@@ -336,7 +324,6 @@ export function WeekCalendar({ parks, weekDates, data, grouped }: WeekCalendarPr
                   weekDates={weekDates}
                   parsedDates={parsedDates}
                   parkData={data[park.id] ?? {}}
-                  today={today}
                 />
               ))}
             </Fragment>