feat: mark copilot toolset as default

The copilot toolset contains important tools like
`create_pull_request_with_copilot` and `get_copilot_job_status` that
should be available by default in the remote MCP server.

By setting `Default: true` on the toolset metadata in OSS, the remote
server automatically picks it up without needing any special handling.
Even though no tools in OSS use this toolset, having the metadata here
allows consistent behavior when the remote server loads defaults.

This is a cleaner approach than having the remote server maintain its
own list of additional default toolsets.

Author: SamMorrowDrums

pkg/github/tools.go

@@ -133,6 +133,7 @@ var (
 	ToolsetMetadataCopilot = inventory.ToolsetMetadata{
 		ID:          "copilot",
 		Description: "Copilot related tools",
+		Default:     true,
 		Icon:        "copilot",
 	}
 	ToolsetMetadataCopilotSpaces = inventory.ToolsetMetadata{