adr-0096-openapi-spec-file-path.md

@objectstack/spec	minor
@objectstack/service-automation	minor
@objectstack/connector-openapi	minor
@objectstack/cli	minor

feat(connector-openapi): resolve providerConfig.spec from a package-relative file path (#3016, ADR-0096 follow-up)

ADR-0096's canonical example authors an OpenAPI-backed instance as providerConfig: { spec: './billing-openapi.json' }, but the landed openapi provider factory only accepted an inline document object or an http(s) URL. The spec union is now complete: inline object | file path | remote URL.

• @objectstack/spec. ConnectorProviderContext gains an optional host-injected loadPackageFile(relativePath) capability (pure type): reads a UTF-8 file resolved against the declaring stack/package root, confined to that root. undefined on hosts without a filesystem.

• @objectstack/service-automation. New packageRoot plugin option (the base for relative file refs; defaults to process.cwd()) and an exported createPackageFileLoader(packageRoot) that implements the confinement guard — absolute paths and ..-escaping paths are rejected — with lazy node:fs/node:path imports so non-Node hosts only fail if a file ref is actually dereferenced. The materializer injects the capability into every provider factory's context. Failures follow the existing reconcile policy: fatal at boot, entry skipped on reload.

• @objectstack/connector-openapi. A string providerConfig.spec that is not an http(s) URL is now read via ctx.loadPackageFile and parsed as an OpenAPI JSON document (clear errors for missing/unreadable files, unparseable JSON, and hosts without package file access).

• @objectstack/cli. serve/dev pass the project folder (the objectstack.config.ts directory) as the automation service's packageRoot, mirroring how the standalone sqlite default is anchored.