dsh-cookie-fix: Limit desktop dsh-auth session cookies to avoid HTTP 431 startup failure

The DeepSeek Harness desktop client, when launched on a random port, accumulates `dsh-auth-*` session cookies on 127.0.0.1. Because the welcome handshake carries the entire cookie jar, this can exceed Node's 16 KiB request header limit, resulting in an HTTP 431 response. `dsh-cookie-fix`, a Host-only bundle maintained by qiongqi-empty, preserves the current cookie plus the 2 most recent old ones during the token exchange at `GET /`, and appends `Max-Age=0` to delete all remaining entries, keeping the jar to no more than 3 cookies. It can be installed via the Plugins page or the command `dsh plugin --profile desktop add`; uninstalling restores the official behavior. If you are already receiving HTTP 431, you must clear the Chromium Cookies before installing the plugin.