feat(acp): add native DeepSeek Harness support

[bobleer]

Summary

• register DeepSeek Harness (dsh) as a built-in native ACP client
• launch the official dsh-acp-demo stdio server directly, with no protocol adapter
• let BitFun install @deepseek-ai/dsh-acp-demo@next locally or on a remote workspace host
• expose the preset in ACP settings and call out the absolute --config path needed for a DSH cordis.yml
• cover built-in metadata, Web UI rendering, and remote-workspace default resolution

Validation

• cargo test -p bitfun-acp (114 passed)
• cargo check -p bitfun-acp --no-default-features --features client
• cargo check -p bitfun-acp --no-default-features --features server
• pnpm --dir src/web-ui run test:run src/infrastructure/config/components/AcpAgentsConfig.test.tsx (11 passed)
• pnpm run type-check:web
• pnpm run check:repo-hygiene
• real local cross-project smoke: BitFun AcpClientService launched published dsh-acp-demo 0.1.0-rc.6 and completed initialize -> session/new -> session/prompt, receiving the replayed PONG response

Remote scenarios

• local workspace: exercised with a real DSH ACP subprocess and prompt round trip
• remote workspace: built-in config fallback is covered by a focused regression test; no live SSH host was exercised
• remote control, Peer Device Mode, and Detached Dispatch: unchanged and not exercised