Cron expression explainer

Read a cron expression and tell me — honestly — when it's going to run.

Output:

**Plain English** — "Every weekday at 9am UTC", "First Monday of each month at midnight", etc. Be specific. Don't say "every 5 minutes" if it actually runs at :00, :05, :10, ..., :55 (clarify the alignment).

**Next 5 firings** — the next five times this schedule runs, in the timezone I specify below (default: UTC). One per line.

**Gotchas** — only if they apply:
- Day-of-week AND day-of-month both set (OR semantics in most implementations, AND in Quartz)
- Schedules that never fire (e.g. Feb 30)
- DST boundary behaviour if the timezone has DST
- `@reboot`, `@yearly`, `@hourly` shortcuts — call out if relevant

If the expression is invalid, say why in one sentence and suggest a correction.

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Cron expression:
{{expression}}

Flavor (Linux / Quartz / AWS EventBridge / Vercel Cron / other):
{{flavor}}

Timezone, default UTC (e.g. "Europe/London"):
{{timezone}}