feat(desktop): Chinese menu, branded icon, and a self-contained harness bundle

Localizes the Electron application menu (文件/编辑/视图/窗口/帮助 plus the
macOS app menu), adds a branded 1024px app icon (window + per-target icns/ico),
and makes the packaged app fully self-contained. Because the harness's pnpm
workspace does not cleanly materialize via pnpm deploy or electron-builder's
dependency resolution (per-package symlinks to vendored sources, native addons,
a separate frontend dist), scripts/build-harness.mjs assembles the repository's
working runtime — node_modules, vendor, packages, native, apps/cli, apps/web,
and a bundled Node binary — into build/harness. electron-builder ships it as an
extraResource at Resources/harness, and the main process spawns that bundled
node + dsh entry when packaged (keeping the system-Node child during dev). Adds
a comprehensive README and ignores the multi-GB harness/dist from git.

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -31,6 +31,10 @@ python/sdk-runtime/src/deepseek_harness_runtime/runtime/node/
 python/**/__pycache__/
 python/**/.pytest_cache/
 apps/web/dist/
+# Packaged desktop app output and the generated self-contained harness runtime
+# (build/harness is a multi-GB copy of node_modules + vendor + native + Node).
+apps/desktop/dist/
+apps/desktop/build/harness/
 .artifacts/
 .playwright-mcp/
 .orig