docs: add LICENSE, README, CHANGELOG, and license headers for npm publish

- Add combined MIT + Apache-2.0 LICENSE file (Copyright 2026 alk.dev)
- Add README.md with quick start for each adapter, lifecycle/close docs,
  operators, EventEnvelope, TypeScript, exports table, upstream attribution
- Add CHANGELOG.md with 0.1.0 entry
- Add SPDX license headers to original source files (WS client, WS server,
  Worker, index barrel)
- Update package.json: add author, repository, homepage, bugs; include
  CHANGELOG.md in files; update description

CHANGELOG.md

@@ -0,0 +1,43 @@
+# Changelog
+
+## 0.1.0
+
+Initial release.
+
+### Core
+
+- `createPubSub` factory with type-safe `publish`/`subscribe` API (adapted from graphql-yoga, MIT)
+- `TypedEventTarget`, `TypedEvent`, `EventEnvelope` types
+- `Repeater` class for backpressure-aware async iteration (inlined from @repeaterjs/repeater, MIT)
+- Operators: `filter`, `map`, `pipe`, `take`, `reduce`, `toArray`, `batch`, `dedupe`, `window`, `flat`, `groupBy`, `chain`, `join`
+
+### Adapters
+
+- **Redis** — `createRedisEventTarget` (peer dep: `ioredis`). Pub/sub with optional prefix and custom serializer.
+- **WebSocket Client** — `createWebSocketClientEventTarget`. Subscribe/publish over a WebSocket connection.
+- **WebSocket Server** — `createWebSocketServerEventTarget`. Fan-out hub for WebSocket spokes with topic-based routing, backpressure handling, and subscription control protocol (`__subscribe`/`__unsubscribe`).
+- **Worker Host** — `createWorkerHostEventTarget`. Communicate with a Worker thread from the main thread.
+- **Worker Thread** — `createWorkerThreadEventTarget`. Communicate with the main thread from inside a Worker.
+
+### Lifecycle
+
+All transport adapters provide a `close()` method for graceful teardown:
+
+- Unsubscribes from all channels/topics
+- Restores any intercepted `onmessage`/`onclose` handlers
+- Removes message listeners
+- Clears internal state maps
+- Does **not** destroy the underlying transport (caller-owned)
+- Idempotent — safe to call multiple times
+
+### Build
+
+- Dual ESM + CJS output via tsup
+- Sub-path exports for each adapter (`@alkdev/pubsub/event-target-redis`, etc.)
+- Zero runtime dependencies (Repeater is inlined)
+- `sideEffects: false`
+- TypeScript declarations (`.d.ts` + `.d.cts`)
+
+### License
+
+Dual-licensed MIT OR Apache-2.0. Portions adapted from graphql-yoga (MIT) and @repeaterjs/repeater (MIT) retain their upstream attribution.