feat: mark copilot toolset as default for remote server

[SamMorrowDrums]

Summary

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.

Changes

• Set Default: true on ToolsetMetadataCopilot

Why this approach?

By setting Default: true on the toolset metadata in OSS, the remote server automatically picks it up via GetDefaultToolsetIDs() without needing any special handling.

Even though no tools in OSS currently use this toolset (the copilot tools are remote-only), having the metadata here allows the remote server to benefit from the default expansion logic already built into the inventory system.

This is cleaner than having the remote server:

1. Override the toolset metadata to set Default: true
2. Build a temporary inventory just to determine defaults
3. Maintain its own list of additional default toolsets

Impact on OSS users

None - since no OSS tools belong to the copilot toolset, this change has no effect on the local MCP server. The toolset will simply be expanded as part of defaults but result in zero additional tools being enabled.

Closes github/github-mcp-server-remote#619

[Copilot]

Pull request overview

This PR attempts to make the copilot toolset default for the remote MCP server by setting Default: true on the ToolsetMetadataCopilot metadata definition in OSS.

Changes:

• Added Default: true field to ToolsetMetadataCopilot in pkg/github/tools.go

[SamMorrowDrums]

@copilot - I'd like to change the approach here. Instead of just setting Default: true on the metadata (which doesn't work because GetDefaultToolsetIDs() only iterates actual tools), let's make the inventory builder handle "default" properly:

Current problem:

• GetDefaultToolsetIDs() collects defaults by iterating through actual tools that have Toolset.Default == true
• If a toolset has Default: true but no tools in the OSS repo use it (like copilot), it won't appear in defaults
• This makes it impossible for remote servers to declare toolsets as defaults via metadata alone

Proposed solution:

1. In the inventory builder, when processing .WithToolsets(), treat "default" as a special keyword
2. Instead of expanding "default" to a list of toolset IDs, add a filter that includes tools where tool.Toolset.Default == true
3. Remove "default" from the toolset list before matching against specific toolset IDs
4. Alternatively, have a method like DefaultToolsetMetadatas() that returns all ToolsetMetadata where Default: true, not just those with tools

This way:

• Setting Default: true on ToolsetMetadataCopilot will actually work
• Remote servers that add tools to the copilot toolset will automatically get them in defaults
• The declarative Default: true on metadata becomes the source of truth

Please implement this change to make Default: true on toolset metadata actually control whether tools in that toolset are included by default.

[Copilot]

@SamMorrowDrums I've opened a new pull request, #1824, to work on those changes. Once the pull request is ready, I'll request review from you.