Bookability: show last-updated timestamp per date column

Backend adds valid_from to DateRateInfo and computes date_last_updated dict
(max valid_from across categories per date). Frontend renders it as a small
timestamp below the date in each column header — time only if today, date+time
if older. Full ISO string in title tooltip.

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

frontend/src/pages/Bookability.tsx

@@ -37,12 +37,14 @@ interface DateRateInfo {
   tariffs: TariffInfo[]
   tariff_count: number
   occupancy?: OccupancyInfo
+  valid_from?: string | null
 }
 
 interface RateMatrixData {
   categories: CategoryInfo[]
   dates: string[]
   matrix: Record<string, Record<string, DateRateInfo>>
+  date_last_updated?: Record<string, string | null>
 }
 
 // Helper functions
@@ -56,6 +58,16 @@ const formatDayOfWeek = (dateStr: string): string => {
   return date.toLocaleDateString('en-GB', { weekday: 'short' })
 }
 
+const formatLastUpdated = (isoStr: string | null | undefined): string => {
+  if (!isoStr) return ''
+  const d = new Date(isoStr)
+  const now = new Date()
+  const isToday = d.toDateString() === now.toDateString()
+  return isToday
+    ? d.toLocaleTimeString('en-GB', { hour: '2-digit', minute: '2-digit' })
+    : d.toLocaleDateString('en-GB', { day: '2-digit', month: 'short' }) + ' ' + d.toLocaleTimeString('en-GB', { hour: '2-digit', minute: '2-digit' })
+}
+
 const isWeekend = (dateStr: string): boolean => {
   const date = new Date(dateStr + 'T00:00:00')
   const day = date.getDay()
@@ -422,6 +434,11 @@ const Bookability: React.FC = () => {
                           >
                             {refreshingDate === dateStr ? '...' : '↻'}
                           </button>
+                          {data.date_last_updated?.[dateStr] && (
+                            <span style={styles.lastUpdated} title={`Rates last fetched: ${data.date_last_updated[dateStr]}`}>
+                              {formatLastUpdated(data.date_last_updated[dateStr])}
+                            </span>
+                          )}
                         </div>
                       </th>
                     ))}
@@ -853,6 +870,12 @@ const styles: Record<string, React.CSSProperties> = {
     fontSize: '13px',
     fontWeight: 600,
   },
+  lastUpdated: {
+    fontSize: '9px',
+    color: 'var(--text-mid)',
+    opacity: 0.7,
+    lineHeight: 1,
+  },
   weekendHeader: {
     background: 'var(--body-bg)',
   },