fix: add graceful termination for Python HTTP server in playground modes (#62)

Adds PYTHON_PID variable and cleanup() function with EXIT/INT/TERM trap
to ensure the background Python HTTP server is always stopped when the
script exits, whether normally or due to an unexpected interruption.

Applies to both playground-single and playground-multisite branches.

Closes #30

bin/setup-test-env.sh

@@ -14,8 +14,24 @@ ENV_TYPE=$1
 # Function to check if a command exists
 command_exists() {
 	command -v "$1" &>/dev/null
+	return $?
 }
 
+# PID of the background Python HTTP server (set when started).
+PYTHON_PID=""
+
+# Function to clean up resources on exit.
+cleanup() {
+	if [ -n "$PYTHON_PID" ]; then
+		echo "Stopping Python HTTP server (PID: $PYTHON_PID)..."
+		kill "$PYTHON_PID" 2>/dev/null || true
+	fi
+	return 0
+}
+
+# Trap EXIT, INT, and TERM so the server is always stopped on script exit.
+trap cleanup EXIT INT TERM
+
 # Function to install wp-env if needed
 install_wp_env() {
 	if ! command_exists wp-env; then
@@ -152,6 +168,8 @@ EOF
 	echo "Starting WordPress Playground..."
 	if command_exists python3; then
 		python3 -m http.server 8888 --directory playground &
+		PYTHON_PID=$!
+		echo "Started Python HTTP server with PID: $PYTHON_PID"
 		echo "Opening WordPress Playground in your browser..."
 		if command_exists open; then
 			open http://localhost:8888/index.html
@@ -259,6 +277,8 @@ EOF
 	echo "Starting WordPress Playground..."
 	if command_exists python3; then
 		python3 -m http.server 8888 --directory playground &
+		PYTHON_PID=$!
+		echo "Started Python HTTP server with PID: $PYTHON_PID"
 		echo "Opening WordPress Playground in your browser..."
 		if command_exists open; then
 			open http://localhost:8888/multisite.html