fix(CQ-WEB-8): Add React.memo to performance-sensitive components

Wrap 7 list-item/card components with React.memo to prevent unnecessary
re-renders when parent components update but props remain unchanged:
- TaskItem (task lists)
- EventCard (calendar views)
- EntryCard (knowledge base)
- WorkspaceCard (workspace list)
- TeamCard (team list)
- DomainItem (domain list)
- ConnectionCard (federation connections)

All are pure components rendered inside .map() loops that depend solely
on their props for rendering output.

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

apps/web/src/components/calendar/EventCard.tsx

@@ -1,3 +1,4 @@
+import React from "react";
 import type { Event } from "@mosaic/shared";
 import { formatTime } from "@/lib/utils/date-format";
 
@@ -5,7 +6,9 @@ interface EventCardProps {
   event: Event;
 }
 
-export function EventCard({ event }: EventCardProps): React.JSX.Element {
+export const EventCard = React.memo(function EventCard({
+  event,
+}: EventCardProps): React.JSX.Element {
   return (
     <div className="bg-white p-3 rounded-lg border-l-4 border-blue-500 shadow-sm hover:shadow-md transition-shadow">
       <div className="flex justify-between items-start mb-1">
@@ -23,4 +26,4 @@ export function EventCard({ event }: EventCardProps): React.JSX.Element {
       {event.location && <p className="text-xs text-gray-500">📍 {event.location}</p>}
     </div>
   );
-}
+});