refactor: fix bugs in calendar logic across duration parsing, RFC compliance, and event handling

- Fix buildDuration() trailing "T" producing invalid ISO 8601 durations
- Fix DURATION_RE missing week (W) support in alerts and invitation parsing
- Fix computeFireTime() end fallback when utcEnd is missing
- Fix recurrenceOverrides patch escaping per RFC 6901 (updateEvent/rsvpEvent)
- Fix layoutOverlappingEvents endMin overflow past 1440
- Fix addDurationToDate() to support weeks and use UTC methods for UTC inputs
- Fix getEffectiveAlerts() null guard on calendarIds
- Fix buildAllDayDuration() DST-safe day calculation using differenceInCalendarDays
- Fix participant matching to check calendarAddress and sendTo (not just email)
- Fix buildParticipantMap() using crypto.randomUUID() instead of hardcoded IDs
- Fix overnight preview negative endMin in week view
- Fix sendImipInvitation() to emit DURATION when utcEnd is absent
- Fix sendImipCancellation() to validate status before sending
- Fix createEvent() to remap all calendarIds for shared calendars
- Fix getCalendarTasks() to clone before mutating @type
- Fix importEvents() error matching to include 'duplicate' and 'conflict'
- Fix looksLikeReply() false positive by requiring organizer + responded attendee
- Fix alert offset regex to require T before minutes
- Fix handleDuplicate() to generate new UID
- Fix formatSnapTime() input clamping
- Replace console.log/error with debug.log/error/warn in iMIP functions

lib/calendar-alerts.ts

@@ -6,6 +6,7 @@ import type {
   Calendar,
   CalendarTask,
 } from '@/lib/jmap/types';
+import { parseDuration } from '@/components/calendar/event-card';
 
 export interface PendingAlert {
   eventId: string;
@@ -17,19 +18,20 @@ export interface PendingAlert {
 
 const STALE_THRESHOLD_MS = 10 * 60 * 1000; // 10 minutes
 
-const DURATION_RE = /^(-?)P(?:(\d+)D)?(?:T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?)?$/;
+const DURATION_RE = /^(-?)P(?:(\d+)W)?(?:(\d+)D)?(?:T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?)?$/;
 
 export function parseAlertOffset(offset: string): number | null {
   const match = DURATION_RE.exec(offset);
   if (!match) return null;
 
   const negative = match[1] === '-';
-  const days = parseInt(match[2] || '0', 10);
-  const hours = parseInt(match[3] || '0', 10);
-  const minutes = parseInt(match[4] || '0', 10);
-  const seconds = parseInt(match[5] || '0', 10);
+  const weeks = parseInt(match[2] || '0', 10);
+  const days = parseInt(match[3] || '0', 10);
+  const hours = parseInt(match[4] || '0', 10);
+  const minutes = parseInt(match[5] || '0', 10);
+  const seconds = parseInt(match[6] || '0', 10);
 
-  const ms = ((days * 24 * 60 * 60) + (hours * 60 * 60) + (minutes * 60) + seconds) * 1000;
+  const ms = ((weeks * 7 * 24 * 60 * 60) + (days * 24 * 60 * 60) + (hours * 60 * 60) + (minutes * 60) + seconds) * 1000;
   return negative ? -ms : ms;
 }
 
@@ -47,9 +49,15 @@ export function computeFireTime(
 
   let baseTime: number;
   if (trigger.relativeTo === 'end') {
-    baseTime = event.utcEnd
-      ? new Date(event.utcEnd).getTime()
-      : new Date(event.start).getTime();
+    if (event.utcEnd) {
+      baseTime = new Date(event.utcEnd).getTime();
+    } else {
+      // Compute end from start + duration
+      const startMs = new Date(event.start).getTime();
+      if (Number.isNaN(startMs)) return null;
+      const durationMin = parseDuration(event.duration);
+      baseTime = startMs + durationMin * 60000;
+    }
   } else {
     baseTime = event.utcStart
       ? new Date(event.utcStart).getTime()
@@ -68,6 +76,7 @@ export function getEffectiveAlerts(
     return event.alerts;
   }
 
+  if (!event.calendarIds) return null;
   const calendarId = Object.keys(event.calendarIds)[0];
   if (!calendarId) return null;