ci: rename the workflow to CI, and fix a README line this PR made stale

The old name — "Run install, format, lint, build, and test on every push" —
enumerated steps rather than naming the workflow, and was wrong in two
directions: it never mentioned the coverage gate, and "on every push" reads
past the two release-gated publish jobs. `CI` renders as `CI / build` and
`CI / coverage` in the checks list, where the job name already carries the
detail.

Display-only: nothing references the name (no badge, no `workflow_run`, no
sibling workflow), and branch protection keys off JOB names, which are unchanged.

Also: README described the publish jobs as `needs: build`, which the previous
commit falsified.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177mPHAdECD18nLLCTwR5rh
Signed-off-by: cliffhall <cliff@futurescale.com>

README.md

@@ -547,7 +547,7 @@ The `smoke:*` scripts run against the in-repo build tree, which is **not** the p
 
 ### Cutting a release
 
-Publishing is automated by two release-gated jobs in [`.github/workflows/main.yml`](.github/workflows/main.yml) (`github.event_name == 'release'`, both `needs: build`):
+Publishing is automated by two release-gated jobs in [`.github/workflows/main.yml`](.github/workflows/main.yml) (`github.event_name == 'release'`, both `needs: [build, coverage]` — so a release cannot publish with either the build job or the coverage gate red):
 
 - **`publish`** — the npm package. Runs `npm run pack:verify` as the pre-publish gate, asserts the release tag matches the root `package.json` version, then `npm publish --access public --provenance` — a single `npm publish` (v2 is not an npm workspace, so there is no v1-style `publish-all`/`--workspaces`), with a signed provenance attestation via GitHub OIDC (`id-token: write`, `environment: release`, `NPM_TOKEN`).
 - **`publish-github-container-registry`** — the container image (see [Docker](#docker)).