test(client): unit-test the pure-logic modules + wire coverage into CI/Sonar

Stand up a client test suite on Node's built-in runner (no vitest/jsdom — the
targeted modules are plain ESM with no browser/DOM deps) and cover the
meaningful client logic, not presentational components:

- api/client.js: the fetch wrapper — always sends the session cookie, maps a
  non-2xx response to a thrown ApiError (body.message → statusText fallback),
  resolves an empty body to null, sets Content-Type for JSON but NOT for raw
  FormData uploads, and builds/encodes query strings + path params.
- lib/shardEvents.js: describe() across event kinds (payload vs live frame,
  actor name→acct→"Someone" fallback, sale pluralization, champ.update
  branches) and the categoryOf table-consistency check.
- data/regionBuckets.js: the presence roll-up, incl. the first-match-wins
  ordering and the "buckets always reconcile to the total" invariant.
- lib/heroLayout.js: parseLayout's version/shape guard and heroBackground's
  default-vs-custom branch.
- lib/format.js: the date/label formatters + relative-time buckets.

Wiring so these actually count:
- client/package.json gains a `test` script (node --test);
- pr-checks.yml runs the client tests as a PR gate;
- sonarqube.yml generates a client LCOV report and sonar-project.properties
  feeds it alongside the server report (SF paths resolve to client/src/...).

43 client tests; coverage on the tested modules: format/regionBuckets/
heroLayout 100%, api client 86%, shardEvents 80%.

Co-Authored-By: Claude <noreply@anthropic.com>

.gitea/workflows/sonarqube.yml

@@ -66,6 +66,18 @@ jobs:
             --test-reporter=lcov --test-reporter-destination=server/coverage/lcov.info \
             server/test/*.test.js
 
+      - name: Generate client test coverage (LCOV)
+        # The client's pure-logic modules (lib/, api/, data/) are plain ESM with no
+        # browser/DOM deps, so they run on the same built-in runner. Run from the
+        # repo root so the `SF:` paths come out as `client/src/...`. No `npm ci`:
+        # the tested modules import only relative files + Node built-ins.
+        run: |
+          mkdir -p client/coverage
+          node --test --experimental-test-coverage \
+            --test-reporter=spec --test-reporter-destination=stdout \
+            --test-reporter=lcov --test-reporter-destination=client/coverage/lcov.info \
+            client/test/*.test.js
+
       - name: Run SonarQube scan
         uses: sonarsource/sonarqube-scan-action@v4
         env: