feat(installer): GitHub Copilot targets — VS Code, Copilot CLI, JetBrains

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>

src/installer/index.ts

@@ -3,7 +3,8 @@
  *
  * Multi-target: writes MCP server config + instructions for the
  * agents the user picks (Claude Code, Cursor, Codex CLI, opencode,
- * Hermes Agent, Gemini CLI, Antigravity IDE).
+ * Hermes Agent, Gemini CLI, Antigravity IDE, Kiro, and GitHub
+ * Copilot in VS Code / the Copilot CLI / JetBrains IDEs).
  * Defaults to the Claude-only behavior for backwards compatibility
  * when no targets are explicitly chosen and nothing else is detected.
  *
@@ -467,8 +468,8 @@ export async function runUninstaller(opts: RunUninstallerOptions): Promise<void>
     const sel = await clack.select({
       message: 'Remove CodeGraph from all your projects, or just this one?',
       options: [
-        { value: 'global' as const, label: 'All projects (global)', hint: '~/.claude, ~/.cursor, ~/.codex, ~/.config/opencode, ~/.hermes, ~/.gemini, ~/.kiro' },
-        { value: 'local'  as const, label: 'Just this project (local)', hint: './.claude, ./.cursor, ./opencode.jsonc, ./.gemini, ./.kiro' },
+        { value: 'global' as const, label: 'All projects (global)', hint: '~/.claude, ~/.cursor, ~/.codex, ~/.config/opencode, ~/.hermes, ~/.gemini, ~/.kiro, ~/.copilot, ~/.config/github-copilot' },
+        { value: 'local'  as const, label: 'Just this project (local)', hint: './.claude, ./.cursor, ./.vscode, ./opencode.jsonc, ./.gemini, ./.kiro' },
       ],
       initialValue: 'global' as const,
     });