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/dxtrade-class.ts

@@ -1764,15 +1764,6 @@ export class DXTradeClient implements PlatformClient {
         };
     }
 
-    /** See PlatformClient: what the session still waits on besides positions
-     *  and working orders. */
-    public restBlocker(): string | null {
-        if (this.ocoPairs.some((p) => !p.done)) return 'an exit pair is still tracked';
-        if (this.pendingFills > 0) return `${this.pendingFills} fill(s) awaited`;
-        if (this.daysFetchInFlight) return 'a history fetch is underway';
-        return null;
-    }
-
     /** Whether a login can't happen until someone acts — the supervisor
      *  doesn't rebuild those (a rebuild can't fix a URL or a password). */
     public get needsAttention(): boolean {