fix: install bun before reflex export to avoid network download failures

- Pre-install bun with retry mechanism before reflex export
- Add bun to PATH to ensure reflex can find it
- Fixes connection reset errors during Docker build

Dockerfile

@@ -41,6 +41,17 @@ RUN curl -fsSL https://deb.nodesource.com/setup_${NODE_VERSION}.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \
     && rm -rf /var/lib/apt/lists/*
 
+# Install bun (required by Reflex for frontend build)
+# Retry mechanism for network issues
+RUN set -ex && \
+    for i in 1 2 3 4 5; do \
+        curl -fsSL https://bun.sh/install | bash && break || \
+        (echo "Attempt $i failed, retrying in 5 seconds..." && sleep 5); \
+    done || (echo "Failed to install bun after 5 attempts" && exit 1)
+
+# Add bun to PATH
+ENV PATH="/root/.bun/bin:${PATH}"
+
 # Copy only requirements first (for better layer caching)
 COPY requirements.txt .
 
@@ -53,6 +64,7 @@ COPY --chown=root:root . .
 
 # Build and export Reflex app for production
 # Export creates .web directory with frontend static files
+# bun is now pre-installed, so reflex export won't try to download it
 RUN python -m reflex export --no-zip
 
 # Aggressive cleanup to reduce layer size