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]/page.tsx

@@ -1174,6 +1174,7 @@ export default function Home() {
                       onChange={(e) => setSearchQuery(e.target.value)}
                       className={cn("pl-9 h-9", searchQuery && "pr-8")}
                       data-search-input
+                      data-tour="search-input"
                     />
                     {searchQuery && (
                       <button
@@ -1579,8 +1580,8 @@ export default function Home() {
                     onNavigatePrev={handleNavigatePrev}
                     onShowShortcuts={() => setShowShortcutsModal(true)}
                     onEditDraft={handleEditDraft}
-                    currentUserEmail={client?.["username"]}
-                    currentUserName={client?.["username"]?.split("@")[0]}
+                    currentUserEmail={client?.getUsername()}
+                    currentUserName={client?.getUsername()?.split("@")[0]}
                     currentMailboxRole={mailboxes.find(m => m.id === selectedMailbox)?.role}
                     mailboxes={mailboxes}
                     selectedMailbox={selectedMailbox}