Gravity subtract: delete the zone bowl and the gas-giant and sun ripples

GetHeight sums body wells only. Removes RadialWaves, GasGiant wave fields,
GasGiantData keys 14-17, PlanetSettings Zone*/Wave* fields, the minimap
gravity range, the Boundary brush and Gravity Waves objects from the scene
and both prefabs. The five bowl fixtures become one WellFixture well at the
origin with unchanged expected numbers. Not yet built or tested: this commit
has not been through the Yggdrasil job.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assets/Scripts/ServerShared/ZoneData.cs

@@ -186,18 +186,6 @@ public class GasGiantData : BodyData
     [JsonProperty("albedoRotationSpeed"), Key(13)]
     public float AlbedoRotationSpeed = 1;
 
-    [JsonProperty("gravRadiusMul")] [Key(14)]
-    public float WaveRadiusMultiplier = 1;
-
-    [JsonProperty("depthMul")] [Key(15)]
-    public float WaveDepthMultiplier = 1;
-
-    [JsonProperty("depthExp")] [Key(16)]
-    public float WaveDepthExponent = 8;
-
-    [JsonProperty("depthExp")] [Key(17)]
-    public float WaveSpeedMultiplier = 8;
-
     [JsonProperty("materialOverrides"), Key(18)]
     public List<string> MaterialOverrides = new List<string>();