Refactor scripts: dedup remainder, remove dead code, perf hardening

Iteration 4 over Assets/Scripts (no component/file splits, no Unity assets touched):

Dedup:
- Route inline cursor-release, material guards, Ctrl-held and undo/redo
  input through existing InputUtil / SetMatFloat helpers
- Add ungated InputUtil.KeyPressedThisFrame; GameplayKeyPressed builds on it
- Unify FindDeep/FindDeepChild into GeometryUtil.FindDeep

Dead code / stale docs:
- Remove unused code-gen bake path (HsvColorPicker.Build, PaintHud factory)
- Drop unreferenced symbols (SubPhaseChanged event, LocalPhaseDuration,
  IsLocalSceneMain, MouseSensitivity.Changed, IsPaused, InSession,
  NetworkControlled, PreviousPose, JointCount, voxel-count accessors)
- Fix incorrect PlayerRole / PaintHud / Pick / PlayerPose docs

Perf / robustness (behaviour-neutral):
- ConcealmentMeter.Evaluate: reuse vertex/topology buffers, two-pointer
  crossing count
- BuildMeshCaches: alloc-free vertex copy, cached topology/UVs
- Guard all PlayerPaintSync LogSync sites behind logSync
- Cache LocalViewerIsHunter / controller / CanShoot / TypingGuard lookups;
  dedup LocalIsHunter with MatchHud
- Change-guard RefreshEmissionColor and HeroCutout.Disarm
- Cache scene/countdown string comparisons per frame
- Grow NonAlloc buffers and log-once on saturation

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

Assets/Scripts/HeroCutout.cs

@@ -137,6 +137,7 @@ public class HeroCutout : MonoBehaviour
         if (Time.time - _lastOccludedTime > Mathf.Max(0f, occlusionHold)) { Disarm(); return; }
 
         // Same hero point feeds the ray and the cone axis, so the gate and the cut volume agree.
+        _armed = true;
         Shader.SetGlobalVector(TargetId, new Vector4(heroPos.x, heroPos.y, heroPos.z, 1f));
         Shader.SetGlobalVector(ParamsId, new Vector4(Mathf.Max(0f, radius * bodyScale), Mathf.Max(1e-4f, feather * bodyScale), Mathf.Max(1e-4f, depthFeather), 0f));
     }
@@ -181,8 +182,15 @@ public class HeroCutout : MonoBehaviour
         return null;
     }
 
+    private bool _armed; // change-guard: Disarm runs every non-armed frame, so it only writes the transition
+
     /// <summary>Clears the "enabled" flag so cutout materials render as plain URP/Lit.</summary>
-    private void Disarm() => Shader.SetGlobalVector(TargetId, Vector4.zero);
+    private void Disarm()
+    {
+        if (!_armed) return;
+        _armed = false;
+        Shader.SetGlobalVector(TargetId, Vector4.zero);
+    }
 
     /// <summary>
     /// Lazily resolves the orbit vcam and its Cinemachine Deoccluder (they may live in a scene that