feat(commands): add /essay-outline command

Transforms a brain dump into a story-structured essay outline.
Pressure tests for a real thesis, applies the Saunders framework
via story-lens skill to validate hook, escalation, and conclusion,
then writes a tight outline to file.

Also fixes stale skill count in README (22 → 24).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

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

@@ -1,7 +1,7 @@
 {
   "name": "compound-engineering",
-  "version": "2.36.0",
-  "description": "AI-powered development tools. 25 agents, 23 commands, 22 skills, 1 MCP server for code review, research, design, and workflow automation.",
+  "version": "2.38.0",
+  "description": "AI-powered development tools. 25 agents, 24 commands, 24 skills, 1 MCP server for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",
     "email": "kieran@every.to",