feat: add analytics page with multi-dimensional filtering - #2005

Greptile Summary

This PR adds a new analytics page for multi-dimensional usage reporting. The main changes are:

• New analytics filters, overview cards, trend charts, pie charts, and detail tables in the frontend.
• A dashboard entry point and authenticated analytics route.
• GraphQL analytics queries for metadata, overview totals, daily stats, and dimension breakdowns.
• Backend aggregation helpers for date, project, channel, model, API key, and user filters.
• English and Chinese localization for the new analytics UI.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The API key and user filter behavior now matches the documented combined-filter semantics.
• Empty user-key matches now return empty analytics results instead of widening the query.

Important Files Changed

_{Reviews (3): Last reviewed commit: "feat: add analytics page with multi-dime..." | Re-trigger Greptile}