fix: align compaction cuts and native usage accounting

src/server/index.ts

@@ -43,3 +43,4 @@ export * from "./compaction.ts";
 export { runPiTurn, piTurnResponse, type PiTurnHandle, type PiTurnSpec } from "./pi/ui-stream.ts";
 export * from "./observability.ts";
 export * from "./model-catalog.ts";
+export { sessionCost } from "./pricing.ts";