Fix container npm install race with flock lock

Frontend/scripts/compose-dev.sh

@@ -3,6 +3,11 @@ set -euo pipefail
 
 cd "$(dirname "$0")/.."
 
+# Serialize dependency install when multiple containers share the same workspace.
+LOCK_FILE=/tmp/clientsflow-npm-install.lock
+exec 9>"$LOCK_FILE"
+flock 9
+
 # Prevent path leakage between host Nuxt build cache and Docker runtime.
 # If any cache contains absolute /Users/... imports, Nitro dev runtime can break in /app.
 mkdir -p .nuxt .output

Frontend/scripts/compose-worker.sh

@@ -3,6 +3,11 @@ set -euo pipefail
 
 cd "$(dirname "$0")/.."
 
+# Serialize dependency install when multiple containers share the same workspace.
+LOCK_FILE=/tmp/clientsflow-npm-install.lock
+exec 9>"$LOCK_FILE"
+flock 9
+
 # Worker container starts from clean image.
 # Install deps without frontend postinstall hooks (nuxt prepare) to keep worker lean/stable.
 npm install --ignore-scripts