Add DeepSeek Harness ACP agent (dsh-acp)

[jeremy9682]

Adds the dsh-acp entry: DeepSeek Harness (https://github.com/deepseek-ai/deepseek-harness) as an Agent Client Protocol agent, via the community bundle @jeremy9682/dsh-acp from https://github.com/jeremy9682/dsh-cursor-codex.

• Distribution: npx (self-provisioning launcher: first run installs the bundle into the user's dsh acp profile, then boots the stdio ACP server).
• Shares $DSH_HOME credentials/session logs with dsh web; requires Node.js >= 22.15 and the dsh launcher.
• End-to-end verified against dsh 0.1.0-rc.6 (initialize → session/new → session/prompt → end_turn).

Note: the npm package publish of @jeremy9682/dsh-acp lands immediately after this PR (repo is public; install path documented in its README).

[jeremy9682]

Update: @jeremy9682/dsh-acp@0.1.0 is now published on npm (https://www.npmjs.com/package/@jeremy9682/dsh-acp, also synced to npmmirror). The npx distribution in this PR is fully functional — verified end-to-end with a fresh dsh plugin --profile acp add @jeremy9682/dsh-acp install followed by an ACP initialize handshake.