#60: CronScheduler with cron jobs and heartbeat intervals

[lapc506]

Summary

• New application/services/cron_scheduler.py with CronScheduler, CronJob, HeartbeatJob
• Standard 5-field cron expression parser (wildcards, ranges, steps, comma lists)
• HeartbeatJob for periodic interval-based checks (e.g. sensor reads every 5min)
• Deterministic tick(now) for testing; max_runs, enable/disable, job lifecycle
• 26 new tests covering parsing, matching, lifecycle, tick behavior, error handling

Closes #60

Config Example

scheduler.add_job(CronJob(
    name="daily-report", cron="0 7 * * *",
    persona_id="analyst", message="Generate metrics report",
))
scheduler.add_heartbeat(HeartbeatJob(
    name="sensor-check", interval_seconds=300,
    persona_id="agronomist", message="Check sensor readings",
))

Test plan

• All 283 unit tests pass
• mypy --strict: 0 errors
• Cron parsing: wildcard, range, step, comma
• Cron matching: specific time, day-of-week
• Heartbeat interval enforcement
• max_runs completion, disabled job skipping
• Callback error graceful handling

Created by Claude Code on behalf of @lapc506

🤖 Generated with Claude Code