## Summary
- **Fix CI build failure**: Auth0Client crashes during Next.js
prerendering when env vars aren't set. Returns a no-op stub (`getSession
→ null`) when domain is missing — semantically correct for static
generation
- **Lazy-load markdown libs (~260kb)**: ReactMarkdown, remarkGfm, and
react-syntax-highlighter were eagerly imported in monaco-diff-viewer but
only rendered when user expands "Generated Tests". Extracted into a
dynamic component
- **Parallelize repo detail query**: `getRepositoryById` ran the
activity count sequentially after the repo lookup. Since `repoId` is
already available, all three queries now run in parallel
## Test plan
- [ ] CI `build` check passes (was failing since #2598)
- [ ] Trace page still renders generated tests correctly when expanded
- [ ] Repository detail page loads correctly with activity status
