Add droid and cursor sync targets, extract shared path helpers

- Add sync --target droid (skills to ~/.factory/skills/)
- Add sync --target cursor (skills + MCP to .cursor/)
- Extract expandHome/resolveTargetHome to src/utils/resolve-home.ts
- Remove duplicated path helpers from convert.ts and install.ts
- Bump version to 0.6.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@every-env/compound-plugin",
-  "version": "0.5.2",
+  "version": "0.6.0",
   "type": "module",
   "private": false,
   "bin": {