fix(brex): surface isPproEnabled in transfer block outputs (#5373)

Tool-level get_transfer/list_transfers already returned is_ppro_enabled
(confirmed present on Brex's live Transfer schema), but the block's
outputs map didn't declare it, so it was unreachable from the workflow
UI. Adds it alongside the other transfer output fields.

apps/sim/blocks/blocks/brex.ts

@@ -591,6 +591,10 @@ export const BrexBlock: BlockConfig<BrexResponse> = {
     createdAt: { type: 'string', description: 'Creation timestamp of the transfer' },
     displayName: { type: 'string', description: 'Display name of the transfer' },
     externalMemo: { type: 'string', description: 'External memo of the transfer' },
+    isPproEnabled: {
+      type: 'boolean',
+      description: 'Whether Principal Protection (PPRO) is enabled for the transfer',
+    },
   },
 }