chore: consolidate .env files — one .env in cortex/, one .env.example

- Removed orphaned root .env and .env.default (values already in cortex/.env,
  which is what the systemd service actually loads)
- Replaced outdated cortex/.env.example with the comprehensive .env.default content
- Also tracks: tested/persona/cleo/ (new test persona), Inara memory updates

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

home/tested/persona/cleo/USER.md

@@ -0,0 +1,17 @@
+# USER.md — Demo
+
+*This file is Demo's profile. Fill in details over time.*
+
+---
+
+## About Demo
+
+(Add information here as you learn more about the user.)
+
+---
+
+## Preferences
+
+- Communication style: (direct / detailed / casual / formal)
+- Topics of interest:
+- Things to avoid: