Add GITHUB_WORKSPACE volume mount to safeoutputs MCP server

[Copilot]

The safeoutputs MCP server receives GITHUB_WORKSPACE as an environment variable but cannot access workspace files because the directory isn't mounted in the container.

Changes

• Added workspace mount: New DefaultWorkspaceMount constant (${{ github.workspace }}:${{ github.workspace }}:rw) added to safeoutputs MCP server configuration
• Updated renderers: Both JSON (renderSafeOutputsMCPConfigWithOptions) and TOML (renderSafeOutputsTOML) formats now include workspace mount
• Fixed test expectations: Updated tests to reflect current MCP Gateway Specification v1.0.0 (type: "stdio" for containerized servers)

Result

{
  "safeoutputs": {
    "container": "node:lts-alpine",
    "mounts": [
      "/opt/gh-aw:/opt/gh-aw:ro",
      "/tmp/gh-aw:/tmp/gh-aw:rw",
      "${{ github.workspace }}:${{ github.workspace }}:rw"  // Added
    ]
  }
}

Follows the same pattern used by Serena MCP server. All 133 workflows recompiled with the new mount configuration.

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