Adds three new installer targets so `codegraph install` can wire the
MCP server into GitHub Copilot surfaces:
- copilot-vscode: .vscode/mcp.json (local) or the VS Code User-dir
mcp.json (global), JSONC-surgical edits, `--path` pinned via
${workspaceFolder} for global installs
- copilot-cli: ~/.copilot/mcp-config.json
- copilot-jetbrains: github-copilot config dir (XDG / %LOCALAPPDATA%)
Detection, install, uninstall, and --print-config are covered for all
three in installer-targets.test.ts, including platform-specific path
resolution.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
