fix(qmd): stop hook group growth on re-sync and harden the warm-up lock

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/hooks/scripts/qmd-warm.sh

@@ -2,6 +2,6 @@
 # SessionStart: warm the QMD index and daemon in the background; never blocks or fails the session.
 script="$HOME/.my-ai-configuration/qmd/qmd-warm.mjs"
 if [ -f "$script" ] && command -v node >/dev/null 2>&1 && git rev-parse --show-toplevel >/dev/null 2>&1; then
-  nohup node "$script" >/dev/null 2>&1 &
+  nohup node "$script" >/dev/null 2>&1 </dev/null &
 fi
 exit 0