feat(web): account data export + sidebar rebrand to "Account"

Step 16 (account / profile) — landed smaller than scoped because turbo-
starter already ships the full /dashboard/settings flow (avatar, name,
email, language, delete-account) and BetterAuth handles security +
sessions out of the box. Reuses that surface; adds the claudemesh-
specific bits only.

- GET /api/my/export — returns a JSON bundle of the user's profile,
  meshes they own, meshes they belong to, invites they've issued, and
  audit events from their OWNED meshes (privacy: don't leak events
  from meshes merely joined). Limited to 5k audit rows.
- ExportData component on /dashboard/settings — button downloads the
  bundle as claudemesh-export-<userId>-<YYYY-MM-DD>.json client-side.
- Sidebar (user group) "settings" label swapped to "account" to match
  the Step 16 naming. Same /dashboard/settings route, same existing
  i18n key ("account" was already in common.json).

No schema changes: user.name (BetterAuth) IS the mesh display name.
meshMember.displayName is the per-join override that lands from the
CLI at registration time.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/app/[locale]/dashboard/(user)/layout.tsx

@@ -36,7 +36,7 @@ const menu = [
     label: "manage",
     items: [
       {
-        title: "settings",
+        title: "account",
         href: pathsConfig.dashboard.user.settings.index,
         icon: Icons.Settings,
       },

apps/web/src/app/[locale]/dashboard/(user)/settings/page.tsx

@@ -7,6 +7,7 @@ import { DeleteAccount } from "~/modules/user/settings/general/delete-account";
 import { EditAvatar } from "~/modules/user/settings/general/edit-avatar";
 import { EditEmail } from "~/modules/user/settings/general/edit-email";
 import { EditName } from "~/modules/user/settings/general/edit-name";
+import { ExportData } from "~/modules/user/settings/general/export-data";
 import { LanguageSwitcher } from "~/modules/user/settings/general/language-switcher";
 
 export const generateMetadata = getMetadata({
@@ -27,6 +28,7 @@ export default async function SettingsPage() {
       <LanguageSwitcher />
       <EditName user={user} />
       <EditEmail user={user} />
+      <ExportData />
       <DeleteAccount />
     </div>
   );