fix: Rider config path and add MCP registry manifest (#604)

- Fix RiderConfigurator to use correct GitHub Copilot config path:
  - Windows: %LOCALAPPDATA%\github-copilot\intellij\mcp.json
  - macOS: ~/Library/Application Support/github-copilot/intellij/mcp.json
  - Linux: ~/.config/github-copilot/intellij/mcp.json
- Add mcp.json for GitHub MCP Registry support:
  - Enables users to install via coplaydev/unity-mcp
  - Uses uvx with mcpforunityserver from PyPI

MCPForUnity/Editor/Clients/Configurators/RiderConfigurator.cs

@@ -10,9 +10,9 @@ namespace MCPForUnity.Editor.Clients.Configurators
         public RiderConfigurator() : base(new McpClient
         {
             name = "Rider GitHub Copilot",
-            windowsConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "JetBrains", "Rider", "mcp.json"),
+            windowsConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "github-copilot", "intellij", "mcp.json"),
-            macConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Library", "Application Support", "JetBrains", "Rider", "mcp.json"),
+            macConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Library", "Application Support", "github-copilot", "intellij", "mcp.json"),
-            linuxConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".config", "JetBrains", "Rider", "mcp.json"),
+            linuxConfigPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".config", "github-copilot", "intellij", "mcp.json"),
             IsVsCodeLayout = true
         })
         { }

mcp.json

@@ -0,0 +1,13 @@
+{
+  "mcpServers": {
+    "unity-mcp": {
+      "type": "stdio",
+      "command": "uvx",
+      "args": [
+        "--from",
+        "mcpforunityserver",
+        "mcp-for-unity"
+      ]
+    }
+  }
+}