fix: use existing node user (UID 1000) instead of useradd

Dockerfile

@@ -1,5 +1,6 @@
 # ── Base image ────────────────────────────────────────────────────────────────
-# node:20-slim is Debian-based — needed for node-pty native compilation
+# node:20-slim is Debian-based — needed for node-pty native compilation.
+# It ships with a built-in "node" user at UID 1000, which is what HF Spaces uses.
 FROM node:20-slim
 
 # ── System dependencies ───────────────────────────────────────────────────────
@@ -11,23 +12,23 @@ RUN apt-get update && \
         g++ \
     && rm -rf /var/lib/apt/lists/*
 
-# ── Non-root user (Hugging Face Spaces runs as UID 1000) ─────────────────────
-RUN useradd -m -u 1000 user
-USER user
-ENV HOME=/home/user \
-    PATH="/home/user/.local/bin:/home/user/.npm-global/bin:${PATH}"
+# ── Use the existing "node" user (UID 1000) ───────────────────────────────────
+# node:20-slim already has a "node" user at UID 1000 — no need to create one.
+USER node
+ENV HOME=/home/node \
+    PATH="/home/node/.npm-global/bin:${PATH}"
 
-# ── Install shellular globally (into user's npm prefix) ──────────────────────
-RUN npm config set prefix /home/user/.npm-global && \
+# ── Install shellular globally (into the node user's prefix) ─────────────────
+RUN npm config set prefix /home/node/.npm-global && \
     npm install -g shellular
 
 # ── App ───────────────────────────────────────────────────────────────────────
-WORKDIR /home/user/app
+WORKDIR /home/node/app
 
-COPY --chown=user:user package*.json ./
+COPY --chown=node:node package*.json ./
 RUN npm install --omit=dev
 
-COPY --chown=user:user . .
+COPY --chown=node:node . .
 
 # ── Runtime ───────────────────────────────────────────────────────────────────
 # Hugging Face Spaces expects port 7860