perf(server): serve timeline pages from retained projection (#7958)

* perf(server): select timeline pages from retained projection

Keep page selection and source coverage indexes with the retained projection so bounded fetches and last-message lookups do not copy or reproject history. Omitted after limits use the existing 200-item store default; explicit zero remains unlimited for released CLI clients.

* test(server): keep timeline page oracle outside production builds

packages/server/src/server/session.ts

@@ -7787,8 +7787,6 @@ export class Session {
   ): Promise<void> {
     const direction: AgentTimelineFetchDirection = msg.direction ?? (msg.cursor ? "after" : "tail");
     const projection = "projected" as const;
-    const requestedLimit = msg.limit;
-    const pageLimit = requestedLimit ?? (direction === "after" ? 0 : 200);
     const cursor: AgentTimelineCursor | undefined = msg.cursor
       ? {
           epoch: msg.cursor.epoch,
@@ -7807,7 +7805,7 @@ export class Session {
       const fetchedControlTimeline = this.agentManager.fetchTimeline(msg.agentId, {
         direction,
         cursor,
-        limit: pageLimit,
+        limit: msg.limit,
       });
       const selectedTimeline = {
         timeline: fetchedControlTimeline,