### Summary
- Add z-restricted spawnBounds to 35 spawners across 15 files to prevent creatures from spawning on incorrect floors
- Building spawners (Pyramid, Fire dungeon, Shame, Vendors) use minZ = spawner_z to prevent spawning below
- Ground level spawners (Graveyards, Outdoors, Tokuno) use minZ = -128 for natural terrain variation
- Multi-floor structures in Ilshenar use floor-specific Z restrictions
### Test plan
- Verify spawners in Fire dungeon building don't spawn creatures on floors below
- Verify Pyramid spawners keep creatures on their respective levels
- Verify ground level spawners (graveyards, outdoors) still spawn correctly on terrain
- Check Ilshenar multi-floor structure spawns creatures on correct floors
723e1a836d