Companion to the backend module migration (LST-64). The Nuxt layer is
auto-detected from frontend/modules/* — no nuxt.config change needed.
- Move page, timer store, time-entries service + DTO and the 6 time-tracking
components into frontend/modules/time-tracking/.
- Rewrite explicit service/DTO imports to ~/modules/time-tracking/* (store and
components stay auto-imported); update the dashboard (index.vue) consumer.
- Route /time-tracking preserved; i18n keys kept in the global locale file.
nuxt build passes; /time-tracking routed.
Matthieu