feat(FN-3956): execute provisioning on approval decisions

The merge completes Step 1 of agent provisioning approval followthrough, executing provisioning actions when approval decisions are made, with supporting documentation in AGENTS.md and docs/agents.md. Test coverage spans provisioning policy, approval routes, gating classifications, extension integra

Fusion-Task-Id: FN-3956

packages/engine/src/index.ts

@@ -11,6 +11,7 @@ export {
   taskDocumentReadParams,
   taskDocumentWriteParams,
   taskLogParams,
+  executeApprovedAgentProvisioning,
 } from "./agent-tools.js";
 export { AgentSemaphore, PRIORITY_MERGE, PRIORITY_EXECUTE, PRIORITY_SPECIFY } from "./concurrency.js";
 export { TriageProcessor, type TriageProcessorOptions } from "./triage.js";