#8701: fix: default enabled to true for cron jobs created via tool API

## Problem Jobs created via the cron tool API (agent tool calls) do not auto-fire because `state.nextRunAtMs` is never computed. ## Root Cause When `enabled` is omitted from the tool call (common — the tool description says it's optional with default `true`), `normalizeCronJobCreate()` does not apply a default. The job is created with `enabled: undefined`, and `computeJobNextRunAtMs()` checks `!job.enabled` which is truthy for `undefined`, returning `undefined` immediately. The CLI path works because it explicitly sets `enabled: !opts.disabled` (defaulting to `true`). ## Fix Add `enabled` to the `applyDefaults` block in `normalizeCronJobInput()`, consistent with how `wakeMode` and `sessionTarget` are already defaulted: ```typescript if (typeof next.enabled !== "boolean") { next.enabled = true; } ``` ## Tests Added two test cases to `normalize.test.ts`: - `defaults enabled to true when omitted` — confirms the fix - `respects explicit enabled: false` — confirms we don't clobber intentional disabling All 7 tests pass. Fixes #8672 <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR fixes cron jobs created via the tool API failing to auto-fire when `enabled` is omitted. `normalizeCronJobInput()` now applies a default `enabled = true` when `applyDefaults` is set (used by `normalizeCronJobCreate()`), aligning behavior with the CLI path and allowing downstream scheduling logic (e.g., `computeJobNextRunAtMs()`) to compute `nextRunAtMs`. The change is localized to the cron job normalization layer (`src/cron/normalize.ts`) and is covered by two new Vitest cases in `src/cron/normalize.test.ts` verifying both the defaulting behavior and that explicit `enabled: false` is preserved. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Change is small, well-scoped, and aligns defaulting behavior between tool API and CLI; added tests cover the new behavior and ensure `enabled: false` is not overridden. - No files require special attention <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->