Rename CLI binary from 'claude' to 'agent' to avoid trademark conflict

Add Learning Series section to README

Create s08.md

Update s00.md

Create s07.md

Create s06.md

Create s05.md

Create s04.md

Update s00.md

Create s03.md

Create s02.md

Create s01.md

Create s00.md

Update .gitignore

Fix timeout on Linux: use SIGINT and elapsed-time detection