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/GeometryUtil.cs

@@ -1,9 +1,21 @@
 using System.Collections.Generic;
 using UnityEngine;
 
-/// <summary>Shared mesh/bounds geometry helpers.</summary>
+/// <summary>Shared mesh/bounds/hierarchy helpers.</summary>
 public static class GeometryUtil
 {
+    /// <summary>Depth-first hierarchy search by name; checks <paramref name="root"/> itself first.</summary>
+    public static Transform FindDeep(Transform root, string name)
+    {
+        if (root.name == name) return root;
+        for (int i = 0; i < root.childCount; i++)
+        {
+            var found = FindDeep(root.GetChild(i), name);
+            if (found) return found;
+        }
+        return null;
+    }
+
     /// <summary>Divides a world scale back out of a freshly baked mesh so it is true unit-scale local
     /// geometry (BakeMesh freezes the transform's lossyScale into the vertices). No-op at scale 1;
     /// <paramref name="scratch"/> is reused so nothing is allocated per bake.</summary>