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.

app/[locale]/contacts/page.tsx

@@ -606,6 +606,7 @@ export default function ContactsPage() {
 
               {/* Panel 2: Contact list */}
               <div
+                data-tour="contacts-list"
                 className={cn(
                   "border-r border-border bg-background flex flex-col flex-shrink-0",
                   isMobile ? "w-full" : "",