feat: simplify installation to single @stable tag

- Remove automatic versioning and dual publishing strategy
- Delete release.yaml and promote-to-stable.yaml workflows
- Add manual-release.yaml for controlled releases
- Remove semantic-release dependencies and config
- Update all documentation to use npx bmad-method install
- Configure NPM to publish to @stable tag by default
- Users can now use simple npx bmad-method install command

package.json

@@ -35,8 +35,6 @@
     "lint:fix": "eslint . --ext .js,.cjs,.mjs,.yaml --fix",
     "list:agents": "node tools/cli.js list:agents",
     "prepare": "husky",
-    "release": "semantic-release",
-    "release:test": "semantic-release --dry-run --no-ci || echo 'Config test complete - authentication errors are expected locally'",
     "validate": "node tools/cli.js validate",
     "version:all": "node tools/bump-all-versions.js",
     "version:all:major": "node tools/bump-all-versions.js major",
@@ -80,8 +78,6 @@
   },
   "devDependencies": {
     "@eslint/js": "^9.33.0",
-    "@semantic-release/changelog": "^6.0.3",
-    "@semantic-release/git": "^10.0.1",
     "eslint": "^9.33.0",
     "eslint-config-prettier": "^10.1.8",
     "eslint-plugin-n": "^17.21.3",
@@ -92,11 +88,13 @@
     "lint-staged": "^16.1.1",
     "prettier": "^3.5.3",
     "prettier-plugin-packagejson": "^2.5.19",
-    "semantic-release": "^22.0.0",
     "yaml-eslint-parser": "^1.2.3",
     "yaml-lint": "^1.7.0"
   },
   "engines": {
     "node": ">=20.10.0"
+  },
+  "publishConfig": {
+    "tag": "stable"
   }
 }