#9088: fix(cron): ensure nextRunAtMs is computed when enabled is undefined (#9056)

## Summary Fixes #9056 - cron.add agent tool doesn't set state.nextRunAtMs, causing jobs to never auto-execute. ## Root Cause When creating a job via the agent tool, <code>input.enabled</code> could be <code>undefined</code>, which passed the typeof check but resulted in <code>enabled</code> being falsy. This caused <code>computeJobNextRunAtMs()</code> to return <code>undefined</code>. ## Changes - Fixed enabled default logic to handle <code>undefined</code>, <code>null</code>, and <code>false</code> correctly - Added explicit state initialization before computing nextRunAtMs - Ensures jobs created via agent tool execute the same as CLI-created jobs ## Testing - [x] Bug #9056 reproduction case now works - [x] Jobs created via agent tool now have state.nextRunAtMs set - [x] Backward compatible with existing job creation paths ## Impact | Method | Before | After | |--------|--------|-------| | Agent tool (cron.add) | ❌ state.nextRunAtMs empty | ✅ state.nextRunAtMs set | | CLI (openclaw cron add) | ✅ Works | ✅ Still works | <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR updates cron job creation so jobs added via the `cron.add` agent tool always get `state.nextRunAtMs` computed. In `src/cron/service/jobs.ts`, the `enabled` defaulting logic is adjusted to treat `undefined`/missing as enabled (while preserving explicit `false`), and `job.state` is defensively initialized before setting `job.state.nextRunAtMs = computeJobNextRunAtMs(job, now)`. This aligns agent-created jobs with the CLI creation path so they auto-execute as expected. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Change is small, localized to cron job creation, and adds defensive state initialization plus clearer enabled defaulting to prevent jobs being created without nextRunAtMs. No behavioral change for explicit enabled=false, and the new code follows an existing pattern already used elsewhere. - src/cron/service/jobs.ts <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->