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/Materials/InvisibleShadowCaster.mat

@@ -0,0 +1,34 @@
+%YAML 1.1
+%TAG !u! tag:unity3d.com,2011:
+--- !u!21 &2100000
+Material:
+  serializedVersion: 6
+  m_ObjectHideFlags: 0
+  m_PrefabParentObject: {fileID: 0}
+  m_PrefabInternal: {fileID: 0}
+  m_Name: InvisibleShadowCaster
+  m_Shader: {fileID: 4800000, guid: 16904b03b50c50540b7b153bca816ca8, type: 3}
+  m_ShaderKeywords: 
+  m_LightmapFlags: 5
+  m_EnableInstancingVariants: 0
+  m_DoubleSidedGI: 0
+  m_CustomRenderQueue: -1
+  stringTagMap: {}
+  disabledShaderPasses: []
+  m_SavedProperties:
+    serializedVersion: 3
+    m_TexEnvs:
+    - _BumpMap:
+        m_Texture: {fileID: 2800000, guid: 27f014ef07a649e448b2e9af69f869df, type: 3}
+        m_Scale: {x: 1, y: 1}
+        m_Offset: {x: 0, y: 0}
+    - _MainTex:
+        m_Texture: {fileID: 2800000, guid: 8d296705ab1a045e28334045f78b2537, type: 3}
+        m_Scale: {x: 1, y: 1}
+        m_Offset: {x: 0, y: 0}
+    m_Floats:
+    - _Cutoff: 0.5
+    - _Shininess: 0.078125
+    m_Colors:
+    - _Color: {r: 1, g: 1, b: 1, a: 1}
+    - _SpecColor: {r: 0.5, g: 0.5, b: 0.5, a: 1}