[claude] benchmarks-website-v3: web UI (landing + chart pages)

[connortsui20]

Summary

Implements the alpha web UI for bench.vortex.dev v3 per
benchmarks-website/planning/components/web-ui.md.
Replaces the placeholder html.rs router introduced in #7637 with two
real pages backed by Maud templates and a vendored Chart.js bundle.

• GET / — landing page that lists every group + chart link from
  /api/groups, rendered via maud.
• GET /chart/{slug} — single Chart.js line chart. Payload is fetched
  server-side via the same api::collect_chart helper used by
  /api/chart/:slug, then embedded inline as a JSON
  <script id="chart-data"> block. No client-side round-trip after
  page load.
• GET /static/... — vendored chart.umd.js (Chart.js 4.4.4, MIT),
  chart-init.js, and style.css. All bundled into the binary via
  include_bytes!.

Slugs are treated as opaque per
02-contracts.md:
the chart handler echoes whatever /api/groups returned straight into
ChartKey::from_slug without parsing or constructing them itself.

api::collect_groups and api::collect_chart are now pub(crate) so
the HTML handlers reuse the same row collectors that back the JSON
read routes — no second SQL implementation.

The chart-init script and the embedded JSON payload between them
satisfy the "no network round-trip after page load" criterion. Inside
the JSON <script> block, </, <!--, and <script are escaped via
JSON-safe string escapes so that benign payload contents can never
break out of the script element.

Tests

tests/web_ui.rs (new, 6 tests):

• landing_page_snapshot — insta snapshot of GET / after seeding
  three envelopes with distinct commit.sha / commit.timestamp
  values.
• chart_page_snapshot — insta snapshot of the rendered tpch-Q1
  chart page; exercises multi-series rendering
  (datafusion:vortex-file-compressed + duckdb:parquet) and verifies
  both the inline <script id="chart-data"> block and the
  /static/chart.umd.js reference.
• chart_page_round_trips_every_slug — every slug returned by
  /api/groups resolves to a 200 chart page with inline data.
• unknown_slug_renders_404 — bogus slug → 404 HTML page.
• empty_landing_page_renders — empty DB → "No data ingested yet."
• static_assets_are_served — content-type checks for the three
  /static/* files.

Pre-existing tests/ingest.rs still passes (10 tests).

Stack inheritance

Inherits the version pins set by #7637 in
benchmarks-website/server/Cargo.toml. The only Cargo change is
insta = { workspace = true } under [dev-dependencies].

Verified locally

• cargo build -p vortex-bench-server
• cargo test -p vortex-bench-server — 10 ingest + 6 web-ui tests
  pass.
• cargo +nightly fmt -p vortex-bench-server -- --check — clean.
• cargo clippy -p vortex-bench-server --all-targets — clean.
• End-to-end smoke test against a running server: INGEST_BEARER_TOKEN=test
  • cargo run, POST two envelopes with different commit shas,
    verified /, /chart/{slug}, the three /static/* routes, and the
    invalid-slug 404 path with curl.

Test plan

• Reviewer runs cargo test -p vortex-bench-server locally.
• Reviewer starts the server (INGEST_BEARER_TOKEN=test cargo run -p vortex-bench-server), POSTs benchmarks-website/server/fixtures/envelope.json,
  and visits http://127.0.0.1:3000/ in a real browser to
  confirm the chart hydrates (this PR was developed in a
  headless sandbox so visual verification was not possible
  here).
• CI green.

Out of scope (deferred per web-ui.md + deferred.md)

Per-commit page, filter UI, full-screen modal, deep links, LTTB
downsampling, lookup-table-driven engine names / colours,
chartjs-plugin-zoom, ratio rendering on compression-size charts, and
geomean summary cards are explicitly deferred and not touched here.

🤖 Generated with Claude Code

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Generated by Claude Code