feat(typert): add compiler-independent type pipeline

docs/core-data-structures/session.md

@@ -302,6 +302,7 @@ The body-stripped declaration keeps the plain class's public constructor, state
  *
  * Plain class (not a Service) — create instances via `ctx.sessions.create()`.
  * Seeding with an existing event log replays/forks a session.
+ * @typert object
  */
 declare class Session {
   /** The ordered surface over this session's event log. */