fix: enhance entrypoint diagnostics and ensure server binary is executable

docker/entrypoint.sh

@@ -1,7 +1,17 @@
 #!/bin/sh
 set -e
 
-echo "[$(date -Iseconds)] Checking dist directory contents:"
-ls -la /app/dist/
+# Print diagnostic info
+echo "[$(date -Iseconds)] Running as user: $(id)"
+echo "[$(date -Iseconds)] Database file: $DATABASE_FILE"
+
+if [ -f "/app/main_server" ]; then
+    echo "[$(date -Iseconds)] main_server found, size: $(stat -c%s /app/main_server) bytes"
+    chmod +x /app/main_server
+else
+    echo "[$(date -Iseconds)] ERROR: /app/main_server not found!"
+    exit 1
+fi
+
 echo "[$(date -Iseconds)] Starting server..."
-exec /app/main_server
+exec /app/main_server