fix(release): align cli and compound-engineering versions with linked-versions plugin

Add release-please linked-versions plugin so cli and compound-engineering
always bump together. Align compound-engineering version to 2.58.0 to
match cli. Previously they diverged at v2.54.0 when commits touched only
one package's path.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugins/compound-engineering/.cursor-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "compound-engineering",
   "displayName": "Compound Engineering",
-  "version": "2.57.0",
+  "version": "2.58.0",
   "description": "AI-powered development tools for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",