feat(web): React yield views — sessions + projects (AUR-270)

[mishanefedov]

Linear: AUR-270

Summary

Visualizes the git-correlation $/commit + $/line endpoints landed in AUR-265.

`/sessions/:id/yield`

• Commits-in-window table — hash · author/date · subject · files · +/− with a bold totals row.
• Five callout stats: cost, commits, lines changed, $/commit, $/line.
• Empty state when the session burned dollars but no commits landed in window.

`/projects/:name/yield`

• Weekly composed chart: cost bars + commit-count bars + $/commit line overlay (right axis).
• Sortable "spend without commit" session list — by cost / lines / files.
• Repo path + four totals (weeks tracked, total cost, total commits, overall $/commit).

Failure modes

Both views handle the API's `ok: false` reasons gracefully — "no store", "session has no project tag", "project is not a git repo under WORKSPACE_ROOT" — with a one-line explainer of what yield needs to compute.

Wiring

Both pages lazy-loaded behind `Suspense`. Nav links surface from `Session.tsx` and `ProjectDetail.tsx`.

Acceptance criteria

• `/sessions/:id/yield` renders commits table + totals + $/commit + $/line callouts.
• `/projects/:name/yield` renders weekly $/commit chart + spend-without-commit list (cost-desc default).
• Both handle `ok: false` cases gracefully.
• Lazy-loaded.

Test plan

• `npm run typecheck` — clean (server)
• `web && npx tsc --noEmit` — clean for new files (one pre-existing `Logs.tsx` unused-var error left alone)
• `npm test` — 369/369 pass
• `npm run build` — server (tsup) + web (vite) both build