feat: simulate_event.py — memory warning / background / battery

[conorluddy]

Problem

Memory warnings, background transitions, and low-battery code paths are skipped in QA because manual repro is tedious. A one-liner trigger unlocks rare-state testing.

Sketch

python scripts/simulate_event.py --memory-warning
python scripts/simulate_event.py --background --bundle-id com.example.app
python scripts/simulate_event.py --foreground --bundle-id com.example.app
python scripts/simulate_event.py --battery-level 0.05 --state unplugged

Wraps xcrun simctl notify_post com.apple.system.lowmemory and simctl io booted setBattery.

Reuses

• resolve_device_identifier
• app_launcher.py patterns for background/foreground transitions

Open questions

• Which Darwin notifications beyond MemoryWarning are useful? (Thermal state, time zone change?)
• Whether to expose raw --notify-post <name> for power users.

Definition of done

• --memory-warning, --background, --foreground, --battery-level, --state working
• --json, --help, SKILL.md updated

Part of the v2.0 coverage expansion epic.