Add see-through X-ray reveal overlay for players

Add a second, additive HDR emission color (_XRayColor) that reveals a
player through walls as a pulsing energy glow, driven during matches:

- Shader: XRayOverlay pass (ZTest Greater, additive) for occluded parts
  plus a matching additive term in the forward fragment for visible
  parts, so the glow shows everywhere and never double-blends. Exposes
  _XRayColor, _XRayPulseSpeed and _XRayPulseStrength for a breathing pulse.
- Render it after opaques via a RenderObjects feature (custom XRayReveal
  light-mode tag) on both PC and Mobile renderers, so the through-wall
  test is depth-sort independent and no longer drops out at some camera
  angles/distances.
- MeshPainter drives _XRayColor alpha through a framerate-independent
  fade (xrayFadeDuration) rather than a hard toggle.
- Reveal is driven per avatar on every client: all remaining un-found
  hiders glow during the Resolution phase, and a hider whose
  ConcealmentMeter EmbeddedPercent exceeds MatchManager.embeddedRevealPercent
  glows via an owner-authoritative NetworkVariable.

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

Assets/Shaders/PlayerCamo.hlsl

@@ -51,6 +51,12 @@ half _HeightNormalIntensity;
 half _OcclusionThreshold;
 float4 _OcclusionMap_TexelSize;
 
+// X-Ray reveal glow (rgb = HDR color, a = fade/opacity master). Consumed here for the VISIBLE parts;
+// the separate XRayOverlay pass (SRPDefaultUnlit) covers the OCCLUDED parts. See CamoForwardFragment.
+half4 _XRayColor;
+half _XRayPulseSpeed;    // 0 = steady; otherwise breathing pulse via _Time (see CamoForwardFragment)
+half _XRayPulseStrength; // modulation depth of the pulse around the authored intensity
+
 // Remaps the painted occlusion/height value into surface AO + a relief normal. Runs after URP's
 // InitializeStandardLitSurfaceData (uv is already parallax-displaced) and before InitializeInputData,
 // so the relief normal flows into inputData.normalWS through the tangent frame.
@@ -285,6 +291,18 @@ void CamoForwardFragment(
 
     half4 color = UniversalFragmentCamo(inputData, surfaceData);
     color.rgb = MixFog(color.rgb, inputData.fogCoord);
+
+    // X-Ray reveal glow on the VISIBLE parts. URP draws the SRPDefaultUnlit XRayOverlay pass BEFORE
+    // this UniversalForward pass (see DrawObjectsPass shader-tag order), so that pass alone can only
+    // survive on OCCLUDED pixels - this opaque forward write overwrites the visible ones. Adding the
+    // same additive term here reveals the glow on the visible parts too. Visible (here) and occluded
+    // (overlay, ZTest Greater) are mutually exclusive by depth => no double contribution. Added
+    // post-fog to match the overlay, which outputs the raw color.
+    // Breathing pulse (sin over _Time) on the glow master, matching the XRayOverlay pass exactly so the
+    // visible and occluded halves stay in phase. Speed 0 => term is 1 => identical to no pulse.
+    half xrayPulse = 1.0h + sin(_Time.y * _XRayPulseSpeed) * _XRayPulseStrength;
+    color.rgb += _XRayColor.rgb * (_XRayColor.a * xrayPulse);
+
     color.a = OutputAlpha(color.a, IsSurfaceTypeTransparent(_Surface));
 
     outColor = color;