fix(auth): allow any authenticated user to trigger sheets sync
The sync-sheets/sync endpoint required area "finanzas", blocking non-finance users from syncing TABLEAU 2025 data. Changed the guard from require_area("finanzas") to get_current_user so any authenticated user can trigger the sync from Mis Dashboards.
Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com