[2.26.4] Add Compound Engineered badge to /workflows:work PRs

- Updated PR template to include badge at bottom linking to plugin repo
- Added badge requirement to quality checklist
- Badge provides attribution and link to the plugin

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

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

@@ -1,6 +1,6 @@
 {
   "name": "compound-engineering",
-  "version": "2.26.3",
+  "version": "2.26.4",
   "description": "AI-powered development tools. 27 agents, 21 commands, 14 skills, 1 MCP server for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",