fix(cron): fix test failures and regenerate protocol files

- Add forceReload option to ensureLoaded to avoid stat I/O in normal
  paths while still detecting cross-service writes in the timer path
- Post isolated job summary back to main session (restores the old
  isolation.postToMainPrefix behavior via delivery model)
- Update legacy migration tests to check delivery.channel instead of
  payload.channel (normalization now moves delivery fields to top-level)
- Remove legacy deliver/channel/to/bestEffortDeliver from payload schema
- Update protocol conformance test for delivery modes
- Regenerate GatewayModels.swift (isolation -> delivery)

src/cli/cron-cli/shared.ts

@@ -66,11 +66,11 @@ export function parseAt(input: string): string | null {
     return null;
   }
   const absolute = parseAbsoluteTimeMs(raw);
-  if (absolute) {
+  if (absolute !== null) {
     return new Date(absolute).toISOString();
   }
   const dur = parseDurationMs(raw);
-  if (dur) {
+  if (dur !== null) {
     return new Date(Date.now() + dur).toISOString();
   }
   return null;