Refactor Assets/Scripts: trim restating comments, minor structure cleanups

Sweep over 48 files (Editor/ excluded): remove comments that restate the
code, condense class summaries, fix three stale doc statements
(HsvColorPicker alpha bar, PaintHud layoutPrefab, MasterVolume
FallbackDefault). Inline two single-use wrappers (IsPointerOverUi,
BuildModes), drop an unused using, replace a magic literal with the
existing ParallaxBase constant, and convert ~10 UnityEngine.Object null
checks to the implicit-bool convention. No serialized fields, signatures,
RPC/NetworkVariable names, defaults, or #if blocks touched.

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

Assets/Scripts/Network/PlayerPaintSync.cs

@@ -607,7 +607,7 @@ public class PlayerPaintSync : NetworkBehaviour
         CopyChunkInto(_snapBuffer, offset, chunk);
     }
 
-    /// <summary>Copies a received chunk into the reassembly buffer, ignoring out-of-bounds offsets.</summary>
+    // Out-of-bounds offsets are ignored rather than thrown on.
     private static void CopyChunkInto(byte[] buffer, int offset, byte[] chunk)
     {
         if (offset >= 0 && offset + chunk.Length <= buffer.Length)
@@ -693,7 +693,6 @@ public class PlayerPaintSync : NetworkBehaviour
         _uploadBuffer = null;
     }
 
-    /// <summary>All connected client ids except the given one (server-side).</summary>
     private ulong[] OtherClientIds(ulong except)
     {
         var ids = NetworkManager.ConnectedClientsIds;