fix: preserve restart routing + thread replies (#1337) (thanks @John-Rood)

Co-authored-by: John-Rood <John-Rood@users.noreply.github.com>
Co-authored-by: Outdoor <outdoor@users.noreply.github.com>

src/infra/restart-sentinel.ts

@@ -33,6 +33,14 @@ export type RestartSentinelPayload = {
   status: "ok" | "error" | "skipped";
   ts: number;
   sessionKey?: string;
+  /** Delivery context captured at restart time to ensure channel routing survives restart. */
+  deliveryContext?: {
+    channel?: string;
+    to?: string;
+    accountId?: string;
+  };
+  /** Thread ID for reply threading (e.g., Slack thread_ts). */
+  threadId?: string;
   message?: string | null;
   doctorHint?: string | null;
   stats?: RestartSentinelStats | null;