[RaphaelFakhri]

Summary

startingDeadlineSeconds is a CronJobSpec field, but the chart renders it in the JobSpec:

• cronjob.yaml renders it under spec.jobTemplate.spec. Strict schema validation rejects the CronJob. Otherwise the API server drops the field and the deadline has no effect.
• job.yaml renders it under the Job spec. The Job API has no such field, so the result is the same.

This change:

• Renders startingDeadlineSeconds under the CronJob spec, next to schedule, and keeps support for 0.
• Stops rendering it on Jobs and removes it from the Job example in values.yaml.
• Updates the CronJob and Job unit tests to match.

Fixes #663

Testing

• Before the change, the updated tests fail: helm-unittest -f tests/cronjob_test.yaml -f tests/job_test.yaml application reports 3 failed, 68 passed.
• After the change, mise run test reports 398 passed. mise run lint passes, and README.md and values.schema.json don't change when regenerated.
• Before the change, kubeconform -strict (Kubernetes 1.31.0) rejects the rendered CronJob (/spec/jobTemplate/spec: additional properties 'startingDeadlineSeconds' not allowed) and Job (/spec). After the change, both resources pass validation.