rename Unity WebGL plugin files to avoid name collisions

Unity flattens WebGL plugins into a single output directory, so the
generic WebSocket.jslib name collided with identically named plugins
from other packages (Photon ships one), failing the build with "Plugin
'WebSocket.jslib' is used from several locations".

Only the file names change -- the exported JavaScript symbols are
unchanged and nothing references these files by name.

Thanks to @Alaadel for the report.

Assisted-by: Claude Opus 4.8

Author: endel

.github/workflows/unity-upm-release.yml

@@ -49,8 +49,8 @@ jobs:
           # Unity-specific files (WebGL platform support)
           cp integrations/Unity/WebSocketWebGL.cs upm-package/WebSocket/
           cp integrations/Unity/WebSocketFactoryWebGL.cs upm-package/WebSocket/
-          cp integrations/Unity/WebSocket.jslib upm-package/WebSocket/
-          cp integrations/Unity/WebSocket.jspre upm-package/WebSocket/
+          cp integrations/Unity/NativeWebSocket.jslib upm-package/WebSocket/
+          cp integrations/Unity/NativeWebSocket.jspre upm-package/WebSocket/
           cp integrations/Unity/colyseus.nativewebsocket.asmdef upm-package/WebSocket/
 
           # Package metadata and samples
@@ -190,8 +190,8 @@ jobs:
         # Unity-specific files
         cp integrations/Unity/WebSocketWebGL.cs upm-package/Assets/WebSocket/
         cp integrations/Unity/WebSocketFactoryWebGL.cs upm-package/Assets/WebSocket/
-        cp integrations/Unity/WebSocket.jslib upm-package/Assets/WebSocket/
-        cp integrations/Unity/WebSocket.jspre upm-package/Assets/WebSocket/
+        cp integrations/Unity/NativeWebSocket.jslib upm-package/Assets/WebSocket/
+        cp integrations/Unity/NativeWebSocket.jspre upm-package/Assets/WebSocket/
         cp integrations/Unity/colyseus.nativewebsocket.asmdef upm-package/Assets/WebSocket/
 
         # Package metadata