feat: add EditEventScreen with calendar and chat mode support

Add a unified event editor that works in two modes:
- Calendar mode: Create/edit events directly via EventService API
- Chat mode: Edit AI-proposed events before confirming them

The chat mode allows users to modify proposed events (title, time,
recurrence) and persists changes both locally and to the server.

New components: DateTimePicker, ScrollableDropdown, useDropdownPosition
New API: PUT /api/chat/messages/:messageId/proposal

apps/server/src/utils/recurrenceExpander.ts

@@ -44,9 +44,13 @@ export function expandRecurringEvents(
     const endTime = new Date(event.endTime);
     const duration = endTime.getTime() - startTime.getTime();
 
+    // For multi-day events: adjust range start back by event duration
+    // to find events that start before rangeStart but extend into the range
+    const adjustedRangeStart = new Date(rangeStart.getTime() - duration);
+
     if (!event.isRecurring || !event.recurrenceRule) {
-      // Non-recurring event: add as-is if within range
-      if (startTime >= rangeStart && startTime <= rangeEnd) {
+      // Non-recurring event: add if it overlaps with the range
+      if (endTime >= rangeStart && startTime <= rangeEnd) {
         expanded.push({
           ...event,
           occurrenceStart: startTime,
@@ -64,9 +68,11 @@ export function expandRecurringEvents(
         `DTSTART:${formatRRuleDateString(startTime)}\nRRULE:${ruleString}`,
       );
 
-      // Get occurrences within the range (using fake UTC dates)
+      // Get occurrences within the adjusted range (using fake UTC dates)
+      // Use adjustedRangeStart to catch multi-day events that start before
+      // rangeStart but still extend into the range
       const occurrences = rule.between(
-        toRRuleDate(rangeStart),
+        toRRuleDate(adjustedRangeStart),
         toRRuleDate(rangeEnd),
         true, // inclusive
       );
@@ -78,6 +84,11 @@ export function expandRecurringEvents(
         const occurrenceStart = fromRRuleDate(occurrence);
         const occurrenceEnd = new Date(occurrenceStart.getTime() + duration);
 
+        // Only include if occurrence actually overlaps with the original range
+        if (occurrenceEnd < rangeStart || occurrenceStart > rangeEnd) {
+          continue;
+        }
+
         // Skip if this occurrence is in the exception dates
         const dateKey = formatDateKey(occurrenceStart);
         if (exceptionSet.has(dateKey)) {