feat: increase RTT from 18 to 19

- Update LeaveBalance model default rtt_total to 19
- Update all tests to verify 19 RTT instead of 18
- Update documentation (design and technical plan)
- Update run.py to bind to 0.0.0.0 for external access
- Update CLAUDE.md deployment instructions

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

run.py

@@ -3,4 +3,4 @@ from app import create_app
 app = create_app()
 
 if __name__ == "__main__":
-    app.run(debug=True)
+    app.run(debug=True, host="0.0.0.0")