feat(docker): enhance entrypoint script with gosu for privilege handling and improve healthcheck command

backend/Dockerfile

@@ -36,7 +36,10 @@ FROM node:22-slim AS runner
 
 WORKDIR /app
 
-# node:22-slim already has user 'node' with UID 1000 - we'll use that
+# Install gosu for reliable privilege dropping
+RUN apt-get update && apt-get install -y --no-install-recommends gosu \
+    && rm -rf /var/lib/apt/lists/* \
+    && gosu nobody true
 
 # Copy built application
 COPY --from=builder /app/node_modules ./node_modules

backend/docker-entrypoint.sh

@@ -5,9 +5,40 @@ set -e
 PUID=${PUID:-1000}
 PGID=${PGID:-1000}
 
+echo "[entrypoint] Starting with PUID=$PUID, PGID=$PGID"
+
 # Ensure data directory exists and has correct ownership
 mkdir -p /app/data
+echo "[entrypoint] Created /app/data"
+
 chown -R "$PUID:$PGID" /app/data
+echo "[entrypoint] Set ownership of /app/data to $PUID:$PGID"
+
+# Check if we can write to data directory
+if touch /app/data/.write-test 2>/dev/null; then
+    rm -f /app/data/.write-test
+    echo "[entrypoint] Write test passed"
+else
+    echo "[entrypoint] ERROR: Cannot write to /app/data"
+    ls -la /app/
+    exit 1
+fi
 
 # Execute the main command as the specified user
-exec runuser -u "#$PUID" -- "$@"
+# Try different methods for dropping privileges
+if command -v gosu >/dev/null 2>&1; then
+    echo "[entrypoint] Using gosu"
+    exec gosu "$PUID:$PGID" "$@"
+elif command -v su-exec >/dev/null 2>&1; then
+    echo "[entrypoint] Using su-exec"
+    exec su-exec "$PUID:$PGID" "$@"
+else
+    echo "[entrypoint] Using su"
+    # Create a temporary user with the specified UID if it doesn't exist
+    if ! id -u "$PUID" >/dev/null 2>&1; then
+        echo "[entrypoint] UID $PUID doesn't exist, running as node user"
+        exec su -s /bin/sh node -c "exec $*"
+    else
+        exec su -s /bin/sh "#$PUID" -c "exec $*"
+    fi
+fi