feat(claude-code): manage the user's global config in the Module

Bring the declarative half of ~/.claude into modules/claude-code and apply
it when the Module is enabled: the global agent instructions (context =
./CLAUDE.md), the skills tree (skills = ./skills), the attention-bell hook,
and settings.json (model = opus plus the Stop/Notification/SessionStart
hook wiring).

Runtime state (projects, plugins, cache, history, sessions) and the
.credentials.json secret are left out, so login survives rebuilds and no
secret enters the repo. Verified against the built home-files that
~/.claude/{CLAUDE.md,settings.json,skills,hooks/attention-bell.sh} are
generated, the hook executable.

modules/claude-code/hooks/attention-bell.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# attention-bell.sh — ring the terminal bell in this Claude session's tmux pane
+# so tmux's monitor-bell flags the (background) window red in the status bar.
+#
+# Claude Code runs hooks as detached subprocesses: they have no controlling
+# terminal, so /dev/tty is unavailable here. But the parent-process chain up to
+# the `claude` process stays intact, and `claude` itself holds the pane's pty.
+# So we walk ancestry to find it and write the bell straight to that tty.
+# (Writing a bare BEL to an explicit /dev/pts/N works even from a detached
+# process — verified against tmux's window_bell_flag.)
+
+pid=$PPID
+while [ "$pid" -gt 1 ] 2>/dev/null; do
+	if [ "$(ps -o comm= -p "$pid" 2>/dev/null)" = claude ]; then
+		tty=$(ps -o tty= -p "$pid" 2>/dev/null | tr -d ' ')
+		[ -n "$tty" ] && [ "$tty" != '?' ] && printf '\a' > "/dev/$tty"
+		exit 0
+	fi
+	pid=$(ps -o ppid= -p "$pid" 2>/dev/null | tr -d ' ')
+	[ -z "$pid" ] && break
+done