feat(openfang): add bundled OpenFang runtime support

- Add prepare-openfang-runtime.mjs script for cross-platform binary download
- Update lib.rs to support binary runtime (fallback to Node.js for legacy)
- Add openfang.cmd/sh launcher scripts
- Update runtime-manifest.json for binary-based runtime
- Add README documentation for bundled runtime architecture

OpenFang binary is downloaded during build, supporting:
- Windows x64/ARM64 (.zip)
- macOS Intel/Apple Silicon (.tar.gz)
- Linux x64/ARM64 (.tar.gz)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/package.json

@@ -7,7 +7,17 @@
     "dev": "vite",
     "build": "tsc && vite build",
     "preview": "vite preview",
-    "tauri": "tauri"
+    "prepare:openclaw-runtime": "node scripts/prepare-openclaw-runtime.mjs",
+    "prepare:openclaw-runtime:dry-run": "node scripts/prepare-openclaw-runtime.mjs --dry-run",
+    "prepare:openfang-runtime": "node scripts/prepare-openfang-runtime.mjs",
+    "prepare:openfang-runtime:dry-run": "node scripts/prepare-openfang-runtime.mjs --dry-run",
+    "prepare:tauri-tools": "node scripts/preseed-tauri-tools.mjs",
+    "prepare:tauri-tools:dry-run": "node scripts/preseed-tauri-tools.mjs --dry-run",
+    "tauri": "tauri",
+    "tauri:build:bundled": "pnpm prepare:openfang-runtime && node scripts/tauri-build-bundled.mjs",
+    "tauri:build:bundled:debug": "pnpm prepare:openfang-runtime && node scripts/tauri-build-bundled.mjs --debug",
+    "tauri:build:nsis:debug": "pnpm prepare:openfang-runtime && node scripts/tauri-build-bundled.mjs --debug --bundles nsis",
+    "tauri:build:msi:debug": "pnpm prepare:openfang-runtime && node scripts/tauri-build-bundled.mjs --debug --bundles msi"
   },
   "dependencies": {
     "@tauri-apps/api": "^2",
@@ -15,6 +25,7 @@
     "lucide-react": "^0.577.0",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",
+    "tweetnacl": "^1.0.3",
     "zustand": "^5.0.11"
   },
   "devDependencies": {