Replace mock token usage with real data from LiteLLM free-tier APIs
(global/activity, global/activity/model, global/spend/models). Adds
per-model breakdown table, loading/error states, usage data models
with serde tests, and i18n keys for all five languages.
Also includes: replace Ollama with LiteLLM proxy, update config,
docker-compose, and provider infrastructure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
