feat(remote): deliver allowlisted Host events through ctx.remote.$on

api/remotes owns the allowlist and its type projection; type-meta owns the shape
predicate, the selection seat, and the internal remote/host-event carrier
signal; api/gateway's Client half turns that signal into $on callbacks through a
private dispatch. apiproxy forwards each allowlisted emission verbatim in one
host/remote-event frame, registered ahead of the derived invalidation frames so
frame order is unchanged, and drops the three per-event variants it replaces.
Owner packages move their Events declarations into client-safe ./types exports,
so a consumer's listener signature is the Host's own declaration.

packages/client/test-runtime/src/index.ts

@@ -39,6 +39,7 @@ export { FixtureSession, TestSessions } from './sessions.ts'
 export { stubSettingsScope } from './settings-scope.ts'
 export type { StubSettingsScope } from './settings-scope.ts'
 export { TestWorkspaces } from './workspaces.ts'
+export { TestRemote } from './remote.ts'
 export { conversationSnapshot, workspaceListState } from './fixtures.ts'
 export type { SessionBehaviorOverrides, SessionFixture, Stabilizer } from './fixtures.ts'
 export { makeTranslate } from './translate.ts'