Slice #3: the job loop — crew, clock, aftermath, betrayals surface

The core state machine closes: lifepath → crew → job → run → aftermath.

JobRunner orchestrates:

• Crew resolves on-site obstacles via skill checks (best-suited member per beat).
• Netrunner descends the NET on the same MissionClock.
• Success = data extracted + ground held + clock intact.
• Economy pays eddies + street cred on success.
• Hidden agendas surface only when their trigger_on condition fired this run.

Proof run (seed 2077, Arasaka extraction): JOB SUCCESS, 10,500 eddies, cred → 7 — and a Corp Plant betrayal surfaces on the Tech while two crew lock in as True Believers.

php bin/job-demo.php --seed=2077 --job=job.arasaka-substation
```

Tests: **34/34** at this commit.