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/settings/account-settings.tsx

@@ -8,13 +8,21 @@ import { formatFileSize } from '@/lib/utils';
 
 export function AccountSettings() {
   const t = useTranslations('settings.account');
-  const { username, serverUrl } = useAuthStore();
+  const { username, serverUrl, isDemoMode, primaryIdentity } = useAuthStore();
   const { quota } = useEmailStore();
 
   const quotaPercentage = quota ? Math.round((quota.used / quota.total) * 100) : 0;
+  const displayName = primaryIdentity?.name || (isDemoMode ? 'Demo User' : undefined);
 
   return (
     <SettingsSection title={t('title')} description={t('description')}>
+      {/* Display Name (show in demo mode or when identity has a name) */}
+      {displayName && (
+        <SettingItem label={t('name_label')}>
+          <span className="text-sm text-foreground">{displayName}</span>
+        </SettingItem>
+      )}
+
       {/* Email Address */}
       <SettingItem label={t('email.label')}>
         <span className="text-sm text-foreground">{username || t('../../common.unknown')}</span>
@@ -49,6 +57,16 @@ export function AccountSettings() {
           </div>
         </SettingItem>
       )}
+
+      {/* Demo mode indicator */}
+      {isDemoMode && (
+        <SettingItem label={t('account_type_label')}>
+          <span className="inline-flex items-center gap-1.5 text-sm font-medium text-amber-600 dark:text-amber-400">
+            <span className="w-2 h-2 rounded-full bg-amber-500 animate-pulse" />
+            {t('demo_account')}
+          </span>
+        </SettingItem>
+      )}
     </SettingsSection>
   );
 }

components/settings/appearance-settings.tsx

@@ -6,6 +6,9 @@ import { useSettingsStore, type ToolbarPosition, type Density } from '@/stores/s
 import { LanguageSwitcher } from '@/components/ui/language-switcher';
 import { SettingsSection, SettingItem, RadioGroup, ToggleSwitch } from './settings-section';
 import { cn } from '@/lib/utils';
+import { useTour } from '@/components/tour/tour-provider';
+import { Button } from '@/components/ui/button';
+import { PlayCircle } from 'lucide-react';
 
 const DENSITY_PREVIEW: Record<Density, { py: string; gap: string; showAvatar: boolean; showPreview: boolean }> = {
   'extra-compact': { py: 'py-0.5', gap: 'gap-1.5', showAvatar: false, showPreview: false },
@@ -61,8 +64,10 @@ function DensityPreview({ density }: { density: Density }) {
 
 export function AppearanceSettings() {
   const t = useTranslations('settings.appearance');
+  const tTour = useTranslations('tour');
   const { theme, setTheme } = useThemeStore();
   const { fontSize, density, animationsEnabled, toolbarPosition, showToolbarLabels, updateSetting } = useSettingsStore();
+  const { startTour, resetTourCompletion } = useTour();
 
   return (
     <SettingsSection title={t('title')} description={t('description')}>
@@ -141,6 +146,19 @@ export function AppearanceSettings() {
           onChange={(checked) => updateSetting('animationsEnabled', checked)}
         />
       </SettingItem>
+
+      {/* Restart Tour */}
+      <SettingItem label={tTour('restart_title')} description={tTour('restart_desc')}>
+        <Button
+          variant="outline"
+          size="sm"
+          onClick={() => { resetTourCompletion(); startTour(); }}
+          className="text-xs h-7"
+        >
+          <PlayCircle className="w-3.5 h-3.5 mr-1" />
+          {tTour('restart_button')}
+        </Button>
+      </SettingItem>
     </SettingsSection>
   );
 }