chore: Bump version to 0.28.0

Updated all component versions:
- bd CLI: 0.27.2 → 0.28.0
- Plugin: 0.27.2 → 0.28.0
- MCP server: 0.27.2 → 0.28.0
- npm package: 0.27.2 → 0.28.0
- Documentation: 0.27.2 → 0.28.0

Generated by scripts/bump-version.sh

npm-package/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@beads/bd",
-  "version": "0.27.2",
+  "version": "0.28.0",
   "description": "Beads issue tracker - lightweight memory system for coding agents with native binary support",
   "main": "bin/bd.js",
   "bin": {