Add two-way emojis to DeepSeek Harness web chat with dsh-stickers

DSH-stickers is a DSH interface enhancement plugin maintained by william-jin-cmu, licensed under BSD-3-Clause open source. The same catalog serves the WebUI emoji picker, the `/sticker` command and the Agent's `send_sticker` tool. There are 24 images in two sets: Blue Whale Girl and Black Whale Girl, among which 14 are public and 10 are only available for agents to send. This article verifies the installation commands, usage and the reason why TUI is not supported for the time being according to the catalog page and GitHub.