chore: Simplify hook messages - remove decorations and emojis

- Plain text messages for SessionEnd and PreCompact hooks
- Use echo instead of printf
- Bump version to 2.1.4

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

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

plugins/learn/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "learn",
   "description": "Claude Learn: Session analysis for patterns and gotchas with domain-based memory, selective saving, and memory hygiene",
-  "version": "2.1.3",
+  "version": "2.1.4",
   "author": {
     "name": "Romfast Team"
   }