Simplify to transport-only: remove call protocol, add EventEnvelope, expand stream operators

- Remove src/call.ts (PendingRequestMap, CallEventSchema, CallError) — call protocol belongs in @alkdev/operations
- Add EventEnvelope type ({ type, id, payload }) as the cross-platform serialization contract
- Simplify createPubSub: replace PubSubPublishArgsByKey tuple model with PubSubEventMap; publish(type, id, payload) and subscribe(type, id) use explicit id for topic scoping
- Update Redis adapter to serialize/deserialize full EventEnvelope
- Expand operators: add take, reduce, toArray, batch, dedupe, window, flat, groupBy, chain, join
- Remove @alkdev/typebox runtime dependency (was only used by call.ts)
- Remove ./call sub-path export from package.json and tsup config
- Update all architecture docs to reflect transport-only scope, add Worker adapter, remove call protocol references
- Remove docs/architecture/call-protocol.md
- Update AGENTS.md with new source layout and transport-only principle

docs/architecture.md

@@ -5,8 +5,8 @@
 | Document | Content |
 |----------|---------|
 | [architecture/README.md](architecture/README.md) | Overview, why this exists, interface contract, consumer context |
-| [architecture/api-surface.md](architecture/api-surface.md) | createPubSub, PubSub types, operators |
-| [architecture/event-targets.md](architecture/event-targets.md) | In-process, Redis, WebSocket adapters |
+| [architecture/api-surface.md](architecture/api-surface.md) | createPubSub, EventEnvelope, PubSub types, operators |
+| [architecture/event-targets.md](architecture/event-targets.md) | In-process, Redis, WebSocket, Worker adapters |
 | [architecture/iroh-transport.md](architecture/iroh-transport.md) | Iroh P2P QUIC transport, framing, identity, hub/spoke |
 | [architecture/build-distribution.md](architecture/build-distribution.md) | Dependencies, project structure, tree-shaking, sub-path exports |