Remove broker session rest

Reverts 062ec07 and 5eb0ea7: every firm's broker session stays logged in
around the clock again, renewing its token on the fixed timer as before.
The tree is back to 6dd2528's. A session_rest row left in settings is
unused.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/platform-client.ts

@@ -85,10 +85,6 @@ export interface PlatformClient {
     lastSyncStartedAt?: number;
     /** Whether the broker still shows a working order on the account. */
     hasWorkingOrders?(accountId: number): boolean;
-    /** Why the session can't be logged out now beyond positions and working
-     *  orders — exit pairs it watches, fills or answers it awaits, a report
-     *  fetch underway — or null (session rest, lib/clients.ts). */
-    restBlocker?(): string | null;
     lastFetchErrors: Record<string, string>;
     lastFetchRaw: Record<string, string>;
     recentEntityEvents: { entityType: string; eventType: string; entity: unknown; ts: number }[];