Add a PreToolUse hook that reminds the main agent not to author test
files directly, and change the implement skill to always use
test-driven-development rather than only where possible.
Wire Stop and Notification hooks in ~/.claude/settings.json to a new
~/.claude/hooks/attention-bell.sh, which rings the terminal bell in the
session pane so tmux monitor-bell flags the background window.
The hook runs detached (no controlling tty), so it walks its process
ancestry to the claude process and writes the BEL to that pane tty.
Also replaces the dead settings.json symlink (pointed at a now-missing
~/wrk/claude path) with a real tracked file.
