feat(jobs): persist lastResult and lastRanAt per job in state

[TerrysPOV]

Problem

After a daemon crash or restart, jobs lose all context of what they were doing. The next run starts cold with no knowledge of whether the previous run succeeded, what it produced, or when it last ran.

Proposed solution

Add lastResult and lastRanAt fields per job in state.json:

{
  "jobs": [{
    "name": "morning-brief",
    "nextAt": 1234567890,
    "lastResult": "ok",
    "lastRanAt": 1234567000
  }]
}

• lastResult: "ok" | "error" | "skipped"
• lastRanAt: Unix timestamp of last completion

The heartbeat prompt can reference lastResult to avoid re-doing completed work after a restart. No breaking changes — fields are additive.

Source

Requested by @Nibbler1250 in #14 (Mega-Post).