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/MeshPainter.Pick.cs

@@ -3,12 +3,7 @@ using UnityEngine;
 
 public partial class MeshPainter
 {
-    // --- Pipette (eyedropper) ---
-    //
-    // A sampling MODE rather than a paint channel: a click (Shift/Ctrl held, or the HUD toggle) reads the
-    // channel values at the hit point into the brush, leaving the brush opacities/alphas untouched - a
-    // pick changes WHAT is painted, not how strongly. Height is adopted only off our own paint mesh.
-    // Per-surface routing: see PickAtScreen.
+    // --- Pipette (eyedropper) --- (semantics: see the pipette tooltip; per-surface routing: PickAtScreen)
 
     [Header("Brush - pipette (eyedropper)")]
     [Tooltip("Pipette mode: a click samples the channel values at the hit point on ANY surface " +