DX sweep: rename to @widgrensit/asobi, point at sdk_demo_backend on :8084, publish on release

[Taure]

Summary

Cross-SDK DX sweep — asobi-js subset. Gets the package npm-publishable and pointed at the canonical demo backend.

• package.json: rename @asobi/client → @widgrensit/asobi (the @asobi scope is unowned; @widgrensit matches the rest of the org). Bump 0.1.0 → 0.2.0. engines.node >=18.0.0 → >=22.0.0 because the SDK relies on the global WebSocket which is only stable in Node 22+. Earlier Node versions can polyfill via ws and assigning to globalThis.WebSocket — documented in the README.
• Full package metadata: repository, homepage, bugs, keywords, exports field, sideEffects: false, publishConfig.access: public.
• prepare script runs tsc so npm install <git-url> produces a built dist/ (currently the package on main ships no dist/, so even the git-URL fallback wouldn't import).
• README: install command updated to @widgrensit/asobi. New "Run a backend first" section pointing at widgrensit/sdk_demo_backend on :8084. Quickstart now subscribes to match.matched before queueing and documents match.matched vs match.joined for SDK consumers (matchmaker push vs reply to a client-initiated match.join). Added a note that on() returns an unsubscribe function.
• CHANGELOG.md added.
• Release workflow: existing tag-on-merge job now also runs npm ci, npm run build, and npm publish --provenance --access public. Requires an NPM_TOKEN repo secret.

Surfaced by the asobi-dx-js agent during the cross-SDK pre-release sweep.

Manual step before merge

Create an NPM_TOKEN repo secret (a publish-scope npm token for the @widgrensit org) so the release workflow can publish.

After merge, the existing release job will tag v0.2.0, create the GitHub release, build, and npm publish automatically. If you want to dry-run first, comment out the Publish to npm step.

Test plan

• npm ci — clean install
• npm run build — produces dist/
• npm pack --dry-run — 25 kB tarball, 98 files, manifest looks right
• Wire NPM_TOKEN and merge to verify publish works

Deferred

• Typed payload generics on on<T>(event) and send<TReq, TRes>(...).
• Vite/Phaser standalone example under examples/.
• Mark deprecated REST API classes with @deprecated JSDoc.
• websocket.ts robustness fixes (_parse_error, _reconnected events, null-channel guards).