feat: Remove deprecated test files and enhance documentation for version 3.3.0 "Nexus Infinitum"

- Deleted obsolete test files: test_mime.go, test_mime_integration.go, and xmpp_client_upload_diagnosis.ipynb.
- Updated README.md to reflect the new version 3.3.0 "Nexus Infinitum" and its features.
- Added comprehensive release notes for version 3.3.0 detailing major enhancements and installation instructions.
- Introduced cleanup script to remove development artifacts while preserving production files.

check-configs.sh

@@ -185,7 +185,7 @@ generate_standard_config() {
     mkdir -p "$(dirname "$config_file")"
     
     cat > "$config_file" << EOF
-# HMAC File Server 3.2 "Tremora del Terra" Configuration
+# HMAC File Server 3.3 "Nexus Infinitum" Configuration
 # Generated for: $deployment_type deployment
 # Generated on: $(date)