Replace head -1 with sed -n '1p' across all install scripts to
prevent SIGPIPE when commands produce multi-line output. head closes
the pipe after reading line 1, causing the writer to receive SIGPIPE
which propagates via pipefail (exit 141). sed reads all input,
avoiding the broken pipe.
Remove install.d/26-bat.sh — bat is already installed and managed
via mise in 30-mise.sh.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>