fix: update Dockerfile comments and permissions for clarity and correctness

Dockerfile

@@ -11,14 +11,15 @@ RUN apt-get update && apt-get install -y \
     procps \
     && rm -rf /var/lib/apt/lists/*
 
-# Copy RustFS binary from official image
-COPY --from=rustfs_base /usr/local/bin/rustfs /usr/local/bin/rustfs
+# Copy RustFS binary from official image (it's at /app/rustfs)
+COPY --from=rustfs_base /app/rustfs /usr/local/bin/rustfs
 
 # Install MinIO Client (mc) for bucket management
 RUN curl -o /usr/local/bin/mc https://dl.min.io/client/mc/release/linux-amd64/mc && \
-    chmod +x /usr/local/bin/mc
+    chmod +x /usr/local/bin/mc && \
+    chmod +x /usr/local/bin/rustfs
 
-# Create directories
+# Create directories with proper permissions
 RUN mkdir -p /data /var/log/rustfs && chmod 777 /data
 
 # Copy configuration files