- swap the crossed branch tests (fish branch checked ~/.bashrc, bash branch
checked ~/.config/fish/config.fish - each never matched its shell)
- install fisher/nvm.fish via 'fish -c' instead of calling fisher from bash
- timestamped backups (nvim.bak-YYYYmmdd-HHMMSS) instead of rm -rf of all
*.bak dirs first - a re-run no longer destroys the original backup
- check git clone result and point at the preserved backup on failure
- load nvm by sourcing its init script (nvm is a function; 'command -v nvm'
never succeeded, so the whole block was dead code)
- guard nvm init sourcing under set +u, fall back to system nodejs
- idempotent rc appends (grep guard), tty-guarded Ctrl+C grace period
- set -euo pipefail with guarded/unguarded audit
- typos: prerequisites, secconds