feat: fetch and render charts for chat answers via /api/v1/charts

feat: sort analyses by updated_at, render data_used in traceability

fix: handle failed AI message persistence per updated Go contract

fix: update traceability endpoint, remove retry logic, and fix report stale version

fix: improve analysis chat rendering, scroll, and traceability persistence

feat: refine analysis workspace navigation and theming

feat: implement dual-backend analysis workspace UX