feat(search-api-server): serve the search API as a bootable process and Docker image

[ddeboer]

Part of #600 (layer 3 of 3: the prebuilt Docker image; the handler, layer 2, shipped in #637).

Adds @lde/search-api-server: the served search API as a bootable process and prebuilt Docker image (ghcr.io/ldelements/search-api-server) – mount a schema-declaration module, set TYPESENSE_* env vars, get /graphql (POST execution, self-contained playground, ?sdl) plus /health, with CORS and depth/cost limits on by default. The composition layer that binds the deliberately engine-agnostic @lde/search-api-graphql handler to @lde/search-typesense.

Design (ADR 15)

• Schema input: a plain-data declaration module, not SHACL. Batteries-included served GraphQL search API + self-contained playground #600 assumed mounted SHACL + search: definitions, but that generator is GraphQL search API #495’s still-open scope. The mount is instead an .mjs default-exporting SearchType declarations (validated at boot by searchSchema() – the “declarations built outside TypeScript” path the runtime validation exists for), because a mounted module cannot resolve bare imports anyway. When GraphQL search API #495 lands, mounted SHACL becomes a second source for the same schema.
• A separate package, because a Typesense-bound server cannot live in @lde/search-api-graphql without breaking its engine-agnosticism.
• The image installs the published package from npm instead of Docker-building the workspace: a few-line Dockerfile, and each image corresponds one-to-one to a provenance-attested npm version. The new docker.yml workflow triggers on the package’s release tag, waits for the npm publish (the release run tags before it publishes), then pushes :<version> and :latest to ghcr.
• Boot-or-fail: schema validation, engine collection resolution and config problems all fail the boot with a diagnosis (config reports every problem in one error), never the first query.

Also

• feat(search): validateSearchType now rejects an unknown field kind (new unknown-kind issue reason). Previously a typo’d kind in a plain-JS declaration passed every kind-dependent rule vacuously – exactly the path the mounted schema module relies on.

Acceptance criteria covered (of #600)

• A prebuilt image serving /graphql + playground from mounted definitions and engine config
• The Dataset Register drops its hand-rolled +server.ts – downstream (Replace the hand-rolled /graphql endpoint with the LDE search GraphQL handler netwerk-digitaal-erfgoed/dataset-register#2282)

After merge

@lde/search-api-server is new on npm: the first version needs the manual Trusted-Publishing bootstrap before the release run and the Docker workflow can succeed.