build(docker): remove node from runtime image

Dockerfile

@@ -1,15 +1,16 @@
+FROM node:24-bookworm-slim AS webui-builder
+
+WORKDIR /app
+COPY webui/package.json webui/package-lock.json ./webui/
+WORKDIR /app/webui
+RUN npm ci
+COPY webui/ ./
+RUN mkdir -p /app/nanobot/web && npm run build
+
 FROM ghcr.io/astral-sh/uv:python3.12-bookworm-slim
 
-# Install Node.js for the WebUI build
 RUN apt-get update && \
-    apt-get install -y --no-install-recommends curl ca-certificates gnupg git bubblewrap openssh-client && \
-    mkdir -p /etc/apt/keyrings && \
-    curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg && \
-    echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_24.x nodistro main" > /etc/apt/sources.list.d/nodesource.list && \
-    apt-get update && \
-    apt-get install -y --no-install-recommends nodejs && \
-    apt-get purge -y gnupg && \
-    apt-get autoremove -y && \
+    apt-get install -y --no-install-recommends ca-certificates git bubblewrap openssh-client && \
     rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
@@ -18,13 +19,13 @@ WORKDIR /app
 # hook from hatch_build.py even for this metadata-only install.
 COPY pyproject.toml README.md LICENSE THIRD_PARTY_NOTICES.md hatch_build.py ./
 RUN mkdir -p nanobot && touch nanobot/__init__.py && \
-    uv pip install --system --no-cache ".[whatsapp]" && \
+    NANOBOT_SKIP_WEBUI_BUILD=1 uv pip install --system --no-cache ".[whatsapp]" && \
     rm -rf nanobot
 
 # Copy the full source and install
 COPY nanobot/ nanobot/
-COPY webui/ webui/
-RUN NANOBOT_FORCE_WEBUI_BUILD=1 uv pip install --system --no-cache ".[whatsapp]"
+COPY --from=webui-builder /app/nanobot/web/dist/ nanobot/web/dist/
+RUN NANOBOT_SKIP_WEBUI_BUILD=1 uv pip install --system --no-cache ".[whatsapp]"
 
 # Create non-root user and config directory
 RUN useradd -m -u 1000 -s /bin/bash nanobot && \