feat: P2.3 Folder Sharing + P2.5 Email Import + P2.6 Contact Import + P2.7 Free/Busy

- P2.3: Folder sharing system — ShareFolderDialog, sharing-store, sharing-settings
- P2.5: Email import (.eml, .tgz, .zip) with dedup and progress
- P2.6: Contact import (vCard + CSV) with auto-mapping
- P2.7: Free/Busy view grid with color-coded slots

components/calendar/event-modal.tsx

@@ -4,13 +4,14 @@ import { useState, useEffect, useCallback, useRef, useMemo } from "react";
 import { useTranslations, useLocale } from "next-intl";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
-import { X, Trash2, Check, Users, CalendarDays, Copy, Pencil, Clock, MapPin, Video, Repeat, Bell, AlignLeft, Plus } from "lucide-react";
+import { X, Trash2, Check, Users, CalendarDays, Copy, Pencil, Clock, MapPin, Video, Repeat, Bell, AlignLeft, Plus, Eye, EyeOff } from "lucide-react";
 import { format, parseISO, addHours, addDays, isSameDay } from "date-fns";
 import type { CalendarEvent, Calendar, CalendarParticipant, CalendarEventAlert, CalendarRecurrenceRule } from "@/lib/jmap/types";
 import { RecurrenceEditor, buildRecurrenceSummary, isSimpleRecurrenceRule } from "./recurrence-editor";
 import { parseDuration, getEventColor } from "./event-card";
 import { buildAllDayDuration, getEventDisplayEndDate, getEventEndDate, getEventStartDate, getPrimaryCalendarId } from "@/lib/calendar-utils";
 import { ParticipantInput, type ParticipantInputHandle } from "./participant-input";
+import { FreeBusyView } from "./free-busy-view";
 import {
   isOrganizer,
   getUserParticipantId,
@@ -351,6 +352,7 @@ export function EventModal({
       .map(p => ({ name: p.name, email: p.email }));
   });
   const [sendInvitations, setSendInvitations] = useState(true);
+  const [showFreeBusy, setShowFreeBusy] = useState(false);
   const participantInputRef = useRef<ParticipantInputHandle>(null);
 
   // Plugin transform: collect conflict warnings for the current event form.
@@ -1074,6 +1076,44 @@ export function EventModal({
               onAdd={handleAddAttendee}
               onRemove={handleRemoveAttendee}
             />
+            {attendees.length > 0 && !allDay && (
+              <div className="mt-2">
+                <Button
+                  variant="outline"
+                  size="sm"
+                  onClick={() => setShowFreeBusy((prev) => !prev)}
+                  className="text-xs"
+                >
+                  {showFreeBusy ? (
+                    <EyeOff className="w-3.5 h-3.5 me-1" />
+                  ) : (
+                    <Eye className="w-3.5 h-3.5 me-1" />
+                  )}
+                  {showFreeBusy ? t("freeBusy.hide") : t("freeBusy.check")}
+                </Button>
+                {showFreeBusy && (
+                  <div className="mt-3">
+                    <FreeBusyView
+                      participants={attendees}
+                      startDate={(() => {
+                        const d = new Date(`${startDate}T${startTime}:00`);
+                        return isNaN(d.getTime()) ? new Date() : d;
+                      })()}
+                      endDate={(() => {
+                        const d = new Date(`${endDate}T${endTime}:00`);
+                        return isNaN(d.getTime()) ? addHours(new Date(`${startDate}T${startTime}:00`), 8) : d;
+                      })()}
+                      onTimeSelect={(start, end) => {
+                        setStartDate(formatDateInput(start));
+                        setStartTime(formatTimeInput(start));
+                        setEndDate(formatDateInput(end));
+                        setEndTime(formatTimeInput(end));
+                      }}
+                    />
+                  </div>
+                )}
+              </div>
+            )}
             {isEdit && statusCounts && (existingParticipants.length > 0) && (
               <p className="text-xs text-muted-foreground mt-1.5">
                 {t("participants.status_summary", {