Plugin workers register event handlers via `ctx.events.on()` in the SDK,
but these subscriptions were never forwarded to the host process. The host
sends events via `notifyWorker("onEvent", ...)` which produces a JSON-RPC
notification (no `id`), but the worker only dispatched `onEvent` as a
request handler — notifications were silently dropped.
Changes:
- Add `events.subscribe` RPC method so workers can register subscriptions
on the host-side event bus during setup
- Handle `onEvent` notifications in the worker notification dispatcher
(previously only `agents.sessions.event` was handled)
- Add `events.subscribe` to HostServices interface, capability map, and
host client handler
- Add `subscribe` handler in host services that registers on the scoped
plugin event bus and forwards matched events to the worker
* public-gh/master:
Drop lockfile from watcher change
Tighten plugin dev file watching
Fix plugin smoke example typecheck
Fix plugin dev watcher and migration snapshot
Clarify plugin authoring and external dev workflow
Expand kitchen sink plugin demos
fix: set AGENT_HOME env var for agent processes
Add kitchen sink plugin example
Simplify plugin runtime and cleanup lifecycle
Add plugin framework and settings UI
# Conflicts:
# packages/db/src/migrations/meta/0029_snapshot.json
# packages/db/src/migrations/meta/_journal.json
