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/GameMode.cs

@@ -21,4 +21,29 @@ public abstract class GameMode
 
     /// <summary>Called every frame while this mode is active.</summary>
     public virtual void Tick() { }
+
+    /// <summary>Enables the player component and sets whether it accepts movement input.</summary>
+    protected void SetPlayerControl(bool controlEnabled)
+    {
+        if (Manager.Player)
+        {
+            Manager.Player.enabled = true;
+            Manager.Player.ControlEnabled = controlEnabled;
+        }
+    }
+
+    /// <summary>Toggles painting on the mesh painter.</summary>
+    protected void SetPainting(bool on)
+    {
+        if (Manager.Painter)
+            Manager.Painter.PaintingEnabled = on;
+    }
+
+    /// <summary>Enables/disables the orbit camera input component. Off while a dedicated camera rig is
+    /// live: the orbit rig would otherwise keep grabbing the cursor and reading the mouse every frame.</summary>
+    protected void SetOrbitInputEnabled(bool on)
+    {
+        if (Manager.CameraInput)
+            Manager.CameraInput.enabled = on;
+    }
 }