fix(core): settle unadvertised tool calls and repair session hook test contexts

packages/core/test/plugin/host.ts

@@ -83,7 +83,9 @@ export function host(overrides: Overrides = {}): PluginContext {
       prompt: () => Effect.die("unused session.prompt"),
       command: () => Effect.die("unused session.command"),
       interrupt: () => Effect.die("unused session.interrupt"),
-      hook: () => Effect.die("unused session.hook"),
+      // Plugins register session hooks during setup, so a bare host accepts the
+      // registration; the callback only runs when a test triggers the request pipeline.
+      hook: () => Effect.succeed({ dispose: Effect.void }),
     },
   }
 }