feat(FN-3953): wire agent provisioning approval policy into engine tools

Merged agent provisioning approval policies into the engine with guard controls that restrict which agents can be created and by whom, integrated through the CLI extension and core policy definitions.

Fusion-Task-Id: FN-3953

docs/settings-reference.md

@@ -212,6 +212,7 @@ Defaults from `DEFAULT_PROJECT_SETTINGS`; key scope from `PROJECT_SETTINGS_KEYS`
 | `verificationFixRetries` | `number` | `2` | Auto-fix retry attempts when verification fails during merge. |
 | `buildTimeoutMs` | `number` | `300000` | Build timeout in milliseconds (5 minutes). |
 | `requirePlanApproval` | `boolean` | `false` | Require manual approval before planning → todo. |
+| `agentProvisioning` | `{ approvalMode?: "always" \| "trusted-only" \| "never"; trustedRoles?: string[]; trustedAgentIds?: string[]; alwaysApproveDelete?: boolean }` | `{}` | Approval policy for `fn_agent_create`/`fn_agent_delete` (`approvalMode` default `trusted-only`, delete approvals default on via `alwaysApproveDelete: true`). |
 | `completionDocumentationMode` | `"off" \| "changeset" \| "changelog"` | `"off"` | Controls triage prompt injection for release-note artifacts in future task specs. `"changeset"` requires `.changeset/*.md` workflow guidance; `"changelog"` requires updating an existing changelog file (without inventing a new one); `"off"` disables this automation. |
 | `specStalenessEnabled` | `boolean` | `false` | Enforce automatic re-planning for stale plans. |
 | `specStalenessMaxAgeMs` | `number` | `21600000` | Spec staleness threshold in ms (6 hours). |