fix(cron): fix timeout, add timestamp validation, enable file sync

Fixes #7667

Task 1: Fix cron operation timeouts
- Increase default gateway tool timeout from 10s to 30s
- Increase cron-specific tool timeout to 60s
- Increase CLI default timeout from 10s to 30s
- Prevents timeouts when gateway is busy with long-running jobs

Task 2: Add timestamp validation
- New validateScheduleTimestamp() function in validate-timestamp.ts
- Rejects atMs timestamps more than 1 minute in the past
- Rejects atMs timestamps more than 10 years in the future
- Applied to both cron.add and cron.update operations
- Provides helpful error messages with current time and offset

Task 3: Enable file sync for manual edits
- Track file modification time (storeFileMtimeMs) in CronServiceState
- Check file mtime in ensureLoaded() and reload if changed
- Recompute next runs after reload to maintain accuracy
- Update mtime after persist() to prevent reload loop
- Dashboard now picks up manual edits to ~/.openclaw/cron/jobs.json

src/cli/gateway-rpc.ts

@@ -15,7 +15,7 @@ export function addGatewayClientOptions(cmd: Command) {
   return cmd
     .option("--url <url>", "Gateway WebSocket URL (defaults to gateway.remote.url when configured)")
     .option("--token <token>", "Gateway token (if required)")
-    .option("--timeout <ms>", "Timeout in ms", "10000")
+    .option("--timeout <ms>", "Timeout in ms", "30000")
     .option("--expect-final", "Wait for final response (agent)", false);
 }