chore(release): 4.21.1 [skip ci]

## [4.21.1](https://github.com/bmadcode/BMAD-METHOD/compare/v4.21.0...v4.21.1) (2025-06-30)

### Bug Fixes

* readme clarifies that the installer handles installs upgrades and expansion installation ([9371a57](9371a5784f))

tools/installer/package.json

@@ -1,6 +1,6 @@
 {
   "name": "bmad-method",
-  "version": "4.21.0",
+  "version": "4.21.1",
   "description": "BMAD Method installer - AI-powered Agile development framework",
   "main": "lib/installer.js",
   "bin": {