feat(embeddings): add quota summary and TokenUsageBar card to embeddings page

[cagedbird043]

Summary

Adds a quota summary and multi-account pooled budget card (TokenUsageBar) to the Embeddings page, aligning its UI design with the main Models page.

Changes

• In server/src/routes/embeddings.ts, parse quota labels (e.g. Cloudflare Neurons/day, HuggingFace monthly credits) and scale by active key count to calculate totalBudget, totalUsed, and per-family budgets in /api/embeddings/usage.
• Export TokenUsageBar and TokenUsageData from FallbackPage.tsx.
• In EmbeddingsPage.tsx, render <TokenUsageBar> at the top of the Embeddings tab when total budget is available.

[tashfeenahmed]

Thanks. Two things before this can go in: (1) parseEmbeddingQuotaLabel hardcodes equivalences (10K neurons/day approximated as 30M tokens/mo, $0.10 as 2M tokens) inferred from quota label strings, plus a silent cloudflare default; those numbers will drift and mislead. If we can't compute a real figure from recorded usage, it's better to show the quota label as-is. (2) TokenUsageBar is imported from FallbackPage into EmbeddingsPage; a shared component should move to components/ rather than being owned by a sibling page. Also note #459 and #457 merged, so a rebase picks up pooled scaling and key load-balancing. Happy to review a revision.