Decision-memory settlement only visits the current ticker

TradingAgentsGraph.settle_pending(ticker) filters pending memory entries to the ticker currently being analyzed. With a rotating screener, pending decisions for symbols that are not selected again remain unresolved indefinitely, even after their holding windows have traded.

Proposed fix: expose an upstream helper that settles every pending ticker, reusing fetch_returns and the existing reflection/write path. Keep entries pending when a full holding-period of price bars is not yet available, and report per-entry settlement failures so scheduled callers can distinguish unresolved outcomes.