feat: update repeated Week Ahead calendar exports (Closes #1214)

frontend/week-calendar.js

@@ -52,7 +52,7 @@
     const lines=['BEGIN:VCALENDAR','VERSION:2.0','PRODID:-//Stackchain//Week Ahead//EN','CALSCALE:GREGORIAN','METHOD:PUBLISH','X-WR-CALNAME:Stackchain Week Ahead',`X-WR-TIMEZONE:${timezone}`,'BEGIN:VTIMEZONE',`TZID:${timezone}`,'END:VTIMEZONE'];
     (blocks||[]).forEach(block=>{
       const day=compact(block.plan_date),reference=block.repository+(block.number!=null?' #'+block.number:'');
-      lines.push('BEGIN:VEVENT',`UID:week-${revision}-${day}-${stableId(block.id)}@stackchain`,`DTSTAMP:${stamp}`,
+      lines.push('BEGIN:VEVENT',`UID:week-${stableId(block.id)}@stackchain`,`SEQUENCE:${Math.max(0,Math.floor(Number(revision)||0))}`,`DTSTAMP:${stamp}`,
         `DTSTART;TZID=${timezone}:${day}T${compact(block.start_time)}00`,`DTEND;TZID=${timezone}:${day}T${compact(block.end_time)}00`,
         `SUMMARY:${escapeText(block.title||'Untitled work')}`,`DESCRIPTION:${escapeText(reference+' · Stackchain Week Ahead')}`,
         `URL:${String(block.url||'')}`,'TRANSP:OPAQUE','END:VEVENT');