feat(core): port v2 command invocation (#34849)

packages/core/test/plugin/command.test.ts

@@ -40,7 +40,6 @@ describe("CommandPlugin.Plugin", () => {
       expect(yield* command.get("review")).toMatchObject({
         name: "review",
         description: "review changes [commit|branch|pr], defaults to uncommitted",
-        subtask: true,
       })
     }),
   )

packages/core/test/plugin/host.ts

@@ -61,6 +61,7 @@ export function host(overrides: Overrides = {}): PluginContext {
       create: () => Effect.die("unused session.create"),
       get: () => Effect.die("unused session.get"),
       prompt: () => Effect.die("unused session.prompt"),
+      command: () => Effect.die("unused session.command"),
       interrupt: () => Effect.die("unused session.interrupt"),
     },
   }