test: cover /resources, /community/governance and the platform-engineering TCG page end to end

[hivecommons-hive]

Test Improvement

Adds tests/e2e/docs-routes.spec.js, covering the three sidebar doc routes no
spec in tests/e2e/ loaded: /resources, /community/governance and
/community/technical-community-groups/platform-engineering. The existing
suite reaches /resources/case-studies and /resources/radar-reports but
never the Resources landing page, and had never requested either community doc.

tests/docs-contract.test.mjs and tests/root-docs-links.test.mjs pin the
source files, and unit coverage for the components these pages render is
already 100% line and region — but all of that reads Markdown off disk. None of
it can see whether the built site serves the route: a page can stay reachable
from the navbar while rendering an empty shell.

What the five cases assert:

• /resources answers < 400, is not the "Page Not Found" page, renders its
  <article> and its nav.menu sidebar, and each pillar link ("Case Studies",
  "Radar Reports") navigates to the route it names and renders content there.
  This page is the only doc on the site whose body is hand-written JSX — it
  imports @docusaurus/Link for the two pillar cards that are the sole entry
  points to the case-study and radar-report tables, so a <Link to> that stops
  resolving under the deployed baseUrl breaks both with nothing to catch it.
• /community/governance renders its article and sidebar and still shows the
  "Source and license" admonition plus the upstream cncf/tab link, without
  which the reproduced text may not be republished.
• /community/technical-community-groups/platform-engineering renders its
  heading and sidebar, and its relative ../governance.md link resolves to
  /community/governance at runtime instead of being emitted as a source path.

Tests only; no production code is touched. Verified locally against a fresh
npm run build:production (E2E_PORT=3137 npx playwright test): 118 tests,
all green — the 113 pre-existing plus these 5. npm run test:unit:coverage:check
still passes (the new file is a .spec.js under tests/e2e/, so node --test
does not pick it up).

Scope

Claims tests/e2e/docs-routes.spec.js and the three routes named above.
Deliberately disjoint from the open hold-gated PRs, none of which touch
tests/e2e/: #810 and #812 (scripts/import-architecture-issue.mjs), #818
(scripts/lib/svg-active-content.mjs), #820
(tests/architecture-catalog-contract.test.mjs), #825
(tests/collect-case-studies.test.mjs, tests/import-architectures.test.mjs,
tests/validate-architecture-assets.test.mjs) and #827 (static/ asset
security).

Related Issue

Closes #828

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Filed by quality agent (hold-gated mode). Human review required.

— hive: agent=quality backend=copilot model=claude-opus-5 copilot=1.0.88

[hivecommons-hive]

Important

Held for human review by the hive's ACMM level gate.

This PR was opened by the "quality" agent while Hive policy required a human checkpoint for that agent. Non-outreach agents are held at ACMM L3–L5; the outreach agent is always held because it publishes project-facing communication.

Hive will automatically remove the hold label once current policy no longer requires a level hold for "quality". If this is an outreach PR, a human must review it and remove the label.