Refactor: extract shared helpers across scripts, trim remaining doc redundancy

Deduplication pass (44 extractions):
- New SmoothedLook: shared smoothed yaw/pitch look tick + view seeding
  (FirstPersonController, FreeCamController)
- New CharacterTeleport: disable-CC-around-teleport idiom (rescue,
  owner position apply, free-cam sync)
- New GeometryUtil: RescaleToUnitScale + TransformBounds (concealment
  meter/volume, skinned collider baker)
- Paint family: canonical map read/write shared between Net and
  Persistence, snapshot decode, backend stroke dispatch, RebuildBackend,
  ResolveSeed, chunked RPC send/gate/copy, CamoKnobs/HeightKnobs
  aggregates, SanitizeFileKey, NewMaskTexture, AdoptAlbedo, FindSlider
- Player/modes: GameMode SetPlayerControl/SetPainting/SetOrbitInputEnabled,
  InputUtil.GameplayKeyPressed, NearestClimbHit, ComputeXRay delegates to
  ComputeResolutionFreeze, FingerIK TryInPlaneAngle
- Match/misc: UnhookSessionCallbacks, SendEmptyNamedMessage, SwapScenes,
  RunSessionOpAsync, CovarianceEigen, CollectClusterPoints, MatchHud
  GUIStyle cache, HsvColorPicker rehook, VoxelCenter

Documentation pass: remove 6 triplicated doc blocks and 2 restating
inline comments left after the previous reduction.

Behavior-neutral; hot-path rasterizer loops intentionally untouched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/Scripts/GeometryUtil.cs

@@ -0,0 +1,43 @@
+using System.Collections.Generic;
+using UnityEngine;
+
+/// <summary>Shared mesh/bounds geometry helpers.</summary>
+public static class GeometryUtil
+{
+    /// <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>
+    public static void RescaleToUnitScale(Mesh baked, Vector3 lossyScale, List<Vector3> scratch)
+    {
+        if (lossyScale.x == 1f && lossyScale.y == 1f && lossyScale.z == 1f) return;
+
+        float ix = lossyScale.x != 0f ? 1f / lossyScale.x : 0f;
+        float iy = lossyScale.y != 0f ? 1f / lossyScale.y : 0f;
+        float iz = lossyScale.z != 0f ? 1f / lossyScale.z : 0f;
+        baked.GetVertices(scratch);
+        for (int i = 0; i < scratch.Count; i++)
+        {
+            Vector3 v = scratch[i];
+            v.x *= ix; v.y *= iy; v.z *= iz;
+            scratch[i] = v;
+        }
+        baked.SetVertices(scratch);
+        baked.RecalculateBounds();
+    }
+
+    /// <summary>World AABB enclosing a local AABB after an affine transform (encapsulates the 8 transformed corners).</summary>
+    public static Bounds TransformBounds(Matrix4x4 m, Bounds local)
+    {
+        Vector3 mn = local.min, mx = local.max;
+        Vector3 c0 = m.MultiplyPoint3x4(mn);
+        Bounds b = new Bounds(c0, Vector3.zero);
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mx.x, mn.y, mn.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mn.x, mx.y, mn.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mn.x, mn.y, mx.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mx.x, mx.y, mn.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mx.x, mn.y, mx.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(new Vector3(mn.x, mx.y, mx.z)));
+        b.Encapsulate(m.MultiplyPoint3x4(mx));
+        return b;
+    }
+}