chore: add node22 bun base image and tune start

Dockerfile.prod

@@ -0,0 +1,29 @@
+# Runtime image with Node 22 + Bun 1.3.2 and build toolchain preinstalled
+FROM node:22-bullseye-slim
+
+ENV BUN_INSTALL=/root/.bun
+ENV PATH="$BUN_INSTALL/bin:$PATH"
+
+RUN apt-get update -y \
+    && apt-get install -y --no-install-recommends \
+       ca-certificates \
+       curl \
+       gnupg \
+       unzip \
+       build-essential \
+       python3 \
+       make \
+       pkg-config \
+       git \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Bun 1.3.2
+RUN curl -fsSL https://bun.sh/install \
+    | bash -s -- bun-v1.3.2 \
+    && ln -sf /root/.bun/bin/bun /usr/local/bin/bun \
+    && ln -sf /root/.bun/bin/bun /usr/local/bin/bunx
+
+WORKDIR /app
+
+# We'll mount the app code at runtime; image just provides runtimes/toolchains.
+CMD ["bash"]