ds-whale-send-button: Replacing the DeepSeek Harness Primary Send Button with a Whale Icon

This plugin is designed to replace the main send button in DeepSeek Harness Web with the official whale logo. Using the CSS `mask` technique, it automatically adapts to both light and dark themes while preserving the original interaction logic. It precisely targets the specific button without affecting other icons. Installation requires a local package and takes effect after a service restart, with support for customizing the icon size and color.