feat: add demo data for emails, files, filters, identities, mailboxes, vacation responses, and JMAP client interface

- Created demo emails with various states (inbox, sent, drafts, trash, etc.) in `emails.ts`.
- Added demo file nodes representing directories and files in `files.ts`.
- Implemented demo Sieve capabilities and scripts in `filters.ts`.
- Defined demo identities for users in `identities.ts`.
- Established demo mailboxes with permissions and counts in `mailboxes.ts`.
- Created a demo vacation response in `vacation.ts`.
- Introduced a comprehensive JMAP client interface in `client-interface.ts` to standardize interactions with the JMAP API.

components/calendar/calendar-toolbar.tsx

@@ -326,7 +326,7 @@ export function CalendarToolbar({
       )}
 
       {!isMobile && (
-        <Button size="sm" onClick={onCreateEvent}>
+        <Button size="sm" onClick={onCreateEvent} data-tour="create-event-button">
           <Plus className="w-4 h-4 mr-1" />
           {t("events.create")}
         </Button>