feat(quick-260630-gbh-01): account settings page — avatar upload + conditional password form

- AuthUser interface: add isLocalUser? + hasAvatar? fields
- uploadAvatarAction: server action forwarding file to POST /users/me/avatar
- AccountSettingsForm: avatar preview with initial fallback + upload; password form only for local users; LDAP notice
- /settings/general/account page mirroring smtp page structure
- SettingsSidebar: Konto link above SMTP link
- de.json + en.json: categoryAccount + account.* keys

apps/web/src/components/settings/settings-sidebar.tsx

@@ -45,6 +45,19 @@ export function SettingsSidebar() {
         </h2>
       </div>
       <nav className="mb-2 flex flex-col gap-1 px-3">
+        <Link
+          href="/settings/general/account"
+          className={`flex items-center rounded-md px-2 py-1.5 text-sm transition-colors ${
+            isActive('/settings/general/account')
+              ? 'bg-sidebar-accent text-sidebar-accent-foreground font-medium'
+              : 'text-sidebar-foreground hover:bg-muted'
+          }`}
+          aria-current={
+            isActive('/settings/general/account') ? 'page' : undefined
+          }
+        >
+          {t('categoryAccount')}
+        </Link>
         <Link
           href="/settings/general/smtp"
           className={`flex items-center rounded-md px-2 py-1.5 text-sm transition-colors ${