No cron job ever produces a run

This is the single most severe bug in this set: it silently disables the entire product. Chronos exists to run scheduled jobs; if the materializer never creates a job_run for a cron job's due occurrences, nothing is ever scheduled, ever, for any job, on any instance -- and there is no error anywhere. Tick() returns nil. Leader election is healthy. The HTTP API is healthy. /readyz reports a leader. Every dashboard looks green while the core function of the service has quietly stopped working entirely -- exactly the kind of bug that survives a superficial health check and is only discovered when a customer notices their job hasn't fired in a day.

pkg/cron/materializer.go's materializeCron caps how far back it will "catch up" missed occurrences after a leader election gap: cutoff := now.Add(24 * time.Hour). cutoff is a positive offset, putting it in the future. The loop only ever runs while next is <= now (for !next.After(now)), so every candidate occurrence is by construction earlier than a cutoff that's 24 hours in the future. next.After(cutoff) is therefore never true, and InsertIfAbsent is never called.

1. Create any cron job (e.g. * * * * *).
2. Call (or wait for) the leader's materializer Tick().
3. Query job_runs for that job -- it will be empty, indefinitely, no matter how long you wait.

A sign error on a duration offset is easy to introduce and, because the surrounding logic (for !next.After(now), if next.After(cutoff)) reads correctly in isolation, easy to miss without tracing through what values cutoff can actually take relative to next.

Read the comment directly above the cutoff line -- it says what the cutoff is supposed to represent ("anything older than 24h of missed ticks is skipped"). Check whether the code one line below matches that description.