feat(cli): add Bun runtime support for ripgrep and CLI spawning

Replace hardcoded 'node' commands with process.execPath to support
Bun runtime alongside Node.js. Add runtime detection and entrypoint
resolution for Bun. Update documentation to reflect multi-runtime support.

cli/scripts/ripgrep_launcher.cjs

@@ -30,4 +30,4 @@ try {
 } catch (error) {
     console.error('Ripgrep error:', error.message);
     process.exit(1);
-}
+}