feat: add continuous learning skill with session examples

Stop hook-based pattern extraction - no README, comments in .sh file.

examples/sessions/2026-01-19-refactor-api.tmp

@@ -0,0 +1,43 @@
+# Session: API Refactor - Error Handling
+**Date:** 2026-01-19
+**Started:** 10:00
+**Last Updated:** 13:30
+
+---
+
+## Current State
+
+Standardizing error handling across all API endpoints. Moving from ad-hoc try/catch to centralized error middleware.
+
+### Completed
+- [x] Created AppError class with status codes
+- [x] Built global error handler middleware
+- [x] Migrated `/users` routes to new pattern
+- [x] Migrated `/products` routes
+
+### Key Findings
+- 47 endpoints with inconsistent error responses
+- Some returning `{ error: message }`, others `{ message: message }`
+- No consistent HTTP status codes
+
+### Error Response Standard
+```javascript
+{
+  success: false,
+  error: {
+    code: 'VALIDATION_ERROR',
+    message: 'Email is required',
+    field: 'email'  // optional, for validation errors
+  }
+}
+```
+
+### Notes for Next Session
+- Migrate remaining routes: `/orders`, `/payments`, `/admin`
+- Add error logging to monitoring service
+
+### Context to Load
+```
+src/middleware/errorHandler.js
+src/utils/AppError.js
+```