Fix completed-history owner receipts and verified attachment cleanup

Use truthful storage absence receipts for MCP deletion and preserve replay fences. Qualify retained chat controls and provider submissions through their actual owners, retain voice and registration obligations, and bound delivery receipt lookup.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/modules/external-agents/index.ts

@@ -4,3 +4,5 @@ export { withExternalAdmissionGuard, withExternalExecutionAdmission, assertNoExt
 export { dotRunnerBroker, createDotRunnerMcpTools } from "./dot.js";
 
 export { notifyExternalAgentSettlement, pendingMuseTerminalBindings, type ExternalAgentSettlementScope } from "./muse-terminal-settlement.js";
+
+export { idleExternalAgentHistoryChecks } from "./idle-history-proof.js";