feat: Deduplicates spawns. Adds spawnbounds where needed. (#2299)

### 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

Distribution/Data/Spawns/shared/ilshenar/Spectre.json

@@ -0,0 +1,23 @@
+[
+  {
+    "type": "Spawner",
+    "guid": "70e1e800-e6dc-4f5c-a610-269930e6c327",
+    "name": "Spawner (310)",
+    "location": [1981, 1059, -28],
+    "map": "Ilshenar",
+    "count": 13,
+    "minDelay": "00:05:00",
+    "maxDelay": "00:10:00",
+    "team": 0,
+    "homeRange": 40,
+    "walkingRange": 40,
+    "entries": [
+      { "name": "Skeleton", "maxCount": 3, "probability": 100 },
+      { "name": "Shade", "maxCount": 2, "probability": 100 },
+      { "name": "Spectre", "maxCount": 2, "probability": 100 },
+      { "name": "Wraith", "maxCount": 2, "probability": 100 },
+      { "name": "Ghoul", "maxCount": 2, "probability": 100 },
+      { "name": "Zombie", "maxCount": 2, "probability": 100 }
+    ]
+  }
+]