fix: build error on arm64

Dockerfile

@@ -13,12 +13,32 @@ ARG TARGETARCH
 ARG TARGETOS
 ENV GOOS=$TARGETOS GOARCH=$TARGETARCH GO111MODULE=on CGO_ENABLED=1
 
-# Install dependencies for cgo
-RUN apk add --no-cache gcc musl-dev
+# Install build dependencies and cross-compilation toolchain
+RUN apk add --no-cache \
+    gcc \
+    musl-dev \
+    g++ \
+    make \
+    linux-headers \
+    wget \
+    tar \
+    && if [ "$TARGETARCH" = "arm64" ]; then \
+    wget -q -O /tmp/cross.tgz https://musl.cc/aarch64-linux-musl-cross.tgz && \
+    tar -xf /tmp/cross.tgz -C /usr/local && \
+    rm /tmp/cross.tgz; \
+    fi
 
 # Build backend
-RUN go install && \
-    go build .
+RUN if [ "$TARGETARCH" = "arm64" ]; then \
+    CC=/usr/local/aarch64-linux-musl-cross/bin/aarch64-linux-musl-gcc \
+    CGO_ENABLED=1 \
+    GOOS=linux \
+    GOARCH=arm64 \
+    go build -o chat -a -ldflags="-extldflags=-static" .; \
+    else \
+    go install && \
+    go build .; \
+    fi
 
 FROM node:18 AS frontend