Consolidate third-party plugins into Assets/Plugins

Move and consolidate many third-party plugin files and metadata from various locations (notably Assets/Third Parties/Plugins 1 and scattered Opsive/Photon folders) into a unified Assets/Plugins directory. Includes DOTween, PrimeTween, Native/BackroomsNoise, Sirenix/Odin Inspector, and Opsive UltimateCharacterController/shared libs, plus updates to several .meta files and removal of obsolete installer/legacy files. This standardizes plugin layout and cleans up duplicate/obsolete assets.

Assets/Third Parties/Opsive/UltimateCharacterController/Scripts/SurfaceSystem/SurfaceImpact.cs

@@ -0,0 +1,18 @@
+/// ---------------------------------------------
+/// Ultimate Character Controller
+/// Copyright (c) Opsive. All Rights Reserved.
+/// https://www.opsive.com
+/// ---------------------------------------------
+
+namespace Opsive.UltimateCharacterController.SurfaceSystem
+{
+    using UnityEngine;
+
+    /// <summary>
+    /// The SurfaceImpact is used to distinguish between different types of collisions for surface effects.
+    /// </summary>
+    public class SurfaceImpact : ScriptableObject
+    {
+        // Intentionally left blank.
+    }
+}