fix(docker): vendor bun binary for image builds

Dockerfile

@@ -1,5 +1,3 @@
-FROM oven/bun:canary-slim AS bun-bin
-
 FROM smanx/opencode:latest AS base
 USER root
 ARG UBUNTU_APT_MIRROR=mirrors.aliyun.com
@@ -11,6 +9,8 @@ ENV PIP_INDEX_URL=${PYPI_INDEX_URL}
 ENV PIP_TRUSTED_HOST=${PYPI_TRUSTED_HOST}
 ENV UV_INDEX_URL=${PYPI_INDEX_URL}
 
+COPY vendor/bun-linux-x64.zip /tmp/bun.zip
+
 RUN sed -i "s|http://archive.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g; s|http://security.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g" /etc/apt/sources.list 2>/dev/null || true && \
     sed -i "s|http://archive.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g; s|http://security.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g" /etc/apt/sources.list.d/*.sources 2>/dev/null || true && \
     apt-get update && apt-get install -y --no-install-recommends \
@@ -19,6 +19,10 @@ RUN sed -i "s|http://archive.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g; s|http:/
     unzip \
     python3 \
     python3-venv && \
+    unzip -q /tmp/bun.zip -d /usr/local && \
+    mv /usr/local/bun-linux-x64 /usr/local/bun && \
+    ln -sf /usr/local/bun/bun /usr/local/bin/bun && \
+    rm -f /tmp/bun.zip && \
     curl -LsSf https://astral.sh/uv/install.sh | sh && \
     ln -s /root/.local/bin/uv /usr/local/bin/uv && \
     ln -sf /usr/bin/python3 /usr/local/bin/python && \
@@ -39,8 +43,6 @@ RUN sed -i "s|http://archive.ubuntu.com|https://${UBUNTU_APT_MIRROR}|g; s|http:/
     pytest && \
     rm -rf /var/lib/apt/lists/*
 
-COPY --from=bun-bin /usr/local/bin/bun /usr/local/bin/bun
-
 FROM base AS deps
 
 WORKDIR /app