Add painted-height HUD sliders for AO shift and relief intensity

Wire three material-backed look sliders (occlusion AO shift, relief normal
intensity, parallax intensity) through the paint HUD, its layout/state
persistence, the .paint slot format (bumped to v4), owner-authoritative
network sync and the runtime reset, mirroring the existing camo-knob path so
they save, restore, replicate and reset alongside the brush values.

Change the occlusion AO mapping from a division threshold to a linear shift:
AO fades from 1 down to (1 - shift) at the deepest painted hole, so a 0 shift
no longer leaves black spots. Enable _NORMALMAP alongside _PARALLAXMAP so URP
transforms the painted relief normal into world space (otherwise it discards
normalTS and the relief is invisible), and pin the added keyword in the build
keep-alive material.

Stop the pipette from picking the occlusion/height value and turn its toggle
off after a pick. Default the knobs to 0.2 shift / 1.4 normal / 1.0 parallax
across the shader, painter, network and HUD fallbacks.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/MeshPainter.Persistence.cs

@@ -16,7 +16,7 @@ public partial class MeshPainter
     // map's canonical Color32 bytes. Raw (not PNG) avoids any sRGB/alpha-premultiply ambiguity and
     // round-trips the exact canonical bytes ReadCanonical produces.
     private const uint PaintFileMagic = 0x504D4843; // 'CHMP' little-endian
-    private const int PaintFileVersion = 3;         // v3: added the per-player material scalars (emission + camo)
+    private const int PaintFileVersion = 4;         // v3: emission + camo scalars; v4: + painted-height knobs
     private const string PaintFileExt = ".paint";
 
     /// <summary>
@@ -26,9 +26,11 @@ public partial class MeshPainter
     /// </summary>
     private struct PaintScalars
     {
-        public bool has; // false = legacy v2 slot with no scalars -> leave the painter's values untouched
+        public bool has;        // false = legacy v2 slot with no scalars -> leave the painter's values untouched
+        public bool hasHeight;  // v4+ painted-height knobs present (occlusion threshold + normal/parallax intensity)
         public float emissionIntensity;
         public float camoHalfLambert, camoHalfLambertBrightness, camoSpecularDampen;
+        public float occlusionThreshold, heightNormalIntensity, parallaxIntensity;
     }
 
     private static string PaintLibraryDir =>
@@ -104,6 +106,11 @@ public partial class MeshPainter
                 w.Write(CamoHalfLambertBrightness);
                 w.Write(CamoSpecularDampen);
 
+                // v4: the painted-height knobs (same material-instance source of truth as the camo knobs).
+                w.Write(OcclusionThreshold);
+                w.Write(HeightNormalIntensity);
+                w.Write(ParallaxIntensity);
+
                 var bytes = new byte[n * 4];
                 for (int mi = 0; mi < MAP_COUNT; mi++)
                 {
@@ -160,6 +167,13 @@ public partial class MeshPainter
             CamoHalfLambertBrightness = scalars.camoHalfLambertBrightness;
             CamoSpecularDampen = scalars.camoSpecularDampen;
         }
+        // v4 slots also carry the painted-height knobs; older slots (v2/v3) leave them at the current value.
+        if (scalars.hasHeight)
+        {
+            OcclusionThreshold = scalars.occlusionThreshold;
+            HeightNormalIntensity = scalars.heightNormalIntensity;
+            ParallaxIntensity = scalars.parallaxIntensity;
+        }
         return true;
     }
 
@@ -190,7 +204,7 @@ public partial class MeshPainter
             {
                 if (r.ReadUInt32() != PaintFileMagic) return null;
                 int ver = r.ReadInt32();
-                if (ver != 2 && ver != PaintFileVersion) return null; // list legacy v2 slots + current
+                if (ver < 2 || ver > PaintFileVersion) return null; // list legacy v2..v3 slots + current
                 return r.ReadString();
             }
         }
@@ -216,7 +230,7 @@ public partial class MeshPainter
             {
                 if (r.ReadUInt32() != PaintFileMagic) return null;
                 int ver = r.ReadInt32();
-                if (ver != 2 && ver != PaintFileVersion) return null; // read legacy v2 + current
+                if (ver < 2 || ver > PaintFileVersion) return null; // read legacy v2..v3 + current
                 r.ReadString(); // display name (header only; not needed for the pixel load)
                 int w = r.ReadInt32();
                 int h = r.ReadInt32();
@@ -232,6 +246,15 @@ public partial class MeshPainter
                     scalars.camoSpecularDampen = r.ReadSingle();
                 }
 
+                // v4+: the painted-height knobs follow the camo scalars.
+                if (ver >= 4)
+                {
+                    scalars.hasHeight = true;
+                    scalars.occlusionThreshold = r.ReadSingle();
+                    scalars.heightNormalIntensity = r.ReadSingle();
+                    scalars.parallaxIntensity = r.ReadSingle();
+                }
+
                 // Resolution change -> ignore rather than smear mismatched data; the brush re-seeds
                 // from the material instead.
                 if (w != textureSize || h != textureSize)