feat(commands): add /essay-edit command for expert essay editing

Pairs with /essay-outline. Runs structural review via story-lens skill
(Saunders framework), then granular line-level editing. Guards against
timid scribe syndrome and preserves author voice via john-voice skill.
Outputs a fully edited essay to docs/essays/.

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

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

@@ -1,7 +1,7 @@
 {
   "name": "compound-engineering",
-  "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.",
+  "version": "2.39.0",
+  "description": "AI-powered development tools. 25 agents, 25 commands, 24 skills, 1 MCP server for code review, research, design, and workflow automation.",
   "author": {
     "name": "Kieran Klaassen",
     "email": "kieran@every.to",