feat(HAI-076): add cross-compilation support for CLI executable builds

- Extend build.ts with cross-compilation targets for multiple platforms/architectures
- Add build:exe:all npm script to package.json for building all targets
- Add cross-compilation tests for build-exe-cross
- Add cross-compilation documentation section to README
- Clean up unused agent log, store, and route code across dashboard/core/engine packages

package.json

@@ -9,6 +9,7 @@
     "dev:ui": "pnpm --filter @hai/dashboard dev",
     "build": "pnpm -r build",
     "build:exe": "pnpm build && pnpm --filter hai build:exe",
+    "build:exe:all": "pnpm build && pnpm --filter hai build:exe:all",
     "typecheck": "pnpm -r typecheck"
   },
   "pnpm": {