Add model: inherit to all agents

All 26 agents now use `model: inherit` so they match whatever model
the user has configured in their main conversation.

Only `lint` keeps `model: haiku` since it's a simple task.

Fixes #69

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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

@@ -1,6 +1,6 @@
 {
   "name": "compound-engineering",
-  "version": "2.23.0",
+  "version": "2.23.1",
   "description": "AI-powered development tools. 27 agents, 21 commands, 13 skills, 2 MCP servers for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",