[FIX] Fix Reflex build errors and improve Docker permissions

- Add state_auto_setters=True to rxconfig.py (fixes Reflex 0.8.9+ deprecation)
- Fix node_modules/.bin permissions in Dockerfile (both files and symlinks)
- Add permission validation in entrypoint.sh
- Fix healthcheck endpoint from /_health to /ping on port 8000
- Add diagnostic commands to Dockerfile for debugging
- Improve permission handling in builder and runtime stages

Fixes permission denied error for react-router during production build

docker/entrypoint.sh

@@ -1,6 +1,18 @@
 #!/bin/bash
 set -e
 
+# Validate node_modules permissions before starting
+if [ -d /app/peikarband/.web/node_modules/.bin ]; then
+    echo "Checking node_modules/.bin permissions..."
+    if [ ! -x /app/peikarband/.web/node_modules/.bin/react-router ]; then
+        echo "WARNING: react-router is not executable, attempting to fix..."
+        chmod +x /app/peikarband/.web/node_modules/.bin/* 2>/dev/null || true
+        echo "Permission fix attempted (may fail if running as non-root)"
+    else
+        echo "✅ react-router is executable"
+    fi
+fi
+
 # Change to the directory containing rxconfig.py
 cd /app/peikarband