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

tools/semantic-release-sync-installer.js

@@ -1,30 +0,0 @@
-/**
- * Semantic-release plugin to sync installer package.json version
- */
-
-const fs = require('node:fs');
-const path = require('node:path');
-
-// This function runs during the "prepare" step of semantic-release
-function prepare(_, { nextRelease, logger }) {
-  // Define the path to the installer package.json file
-  const file = path.join(process.cwd(), 'tools/installer/package.json');
-
-  // If the file does not exist, skip syncing and log a message
-  if (!fs.existsSync(file)) return logger.log('Installer package.json not found, skipping');
-
-  // Read and parse the package.json file
-  const package_ = JSON.parse(fs.readFileSync(file, 'utf8'));
-
-  // Update the version field with the next release version
-  package_.version = nextRelease.version;
-
-  // Write the updated JSON back to the file
-  fs.writeFileSync(file, JSON.stringify(package_, null, 2) + '\n');
-
-  // Log success message
-  logger.log(`Synced installer package.json to version ${nextRelease.version}`);
-}
-
-// Export the prepare function so semantic-release can use it
-module.exports = { prepare };