feat(kit): extract the protocol into @padosoft/ecr17-kit and adopt @padosoft/native-modules

[47PADO47]

Stacked on #23 (feat/windows-support). Merge that first.

Summary

Splits the module into a native library and a React Native binding, so the protocol can be used by fully native apps (Windows C++, and later Swift/Kotlin, .NET) as well as by React Native.

kit/ — @padosoft/ecr17-kit (new)

A React-free C++20 library, namespace padosoft::ecr17, headers <Ecr17Kit/…>:

• Protocol core: Lcr, PacketCodec, Ecr17Protocol, Ecr17Response, Ecr17Session and RetryPolicy. Moved unchanged apart from the namespace, plus its own LrcMode.
• Ecr17Client: auto-connect, the pre-send liveness probe and the money-safe retry policy. This orchestration used to live in HybridEcr17Client, where nothing tested it except RetryPolicy.
• WinsockTransport: the Winsock code from feat(windows): React Native Windows support (Nitro install DLL + Winsock transport) #23, now a plain C++ Transport with no Nitro. Its loopback tests no longer need Nitro or nitrogen.
• Packaging:
  • CMake target Ecr17Kit::Ecr17Kit, installable with find_package support;
  • an Ecr17Kit pod (C++ sources, public <Ecr17Kit/…> headers);
  • an Expo config plugin (adds the pod; createNativeKitPlugin from @padosoft/expo);
  • a nativeKit.windows manifest, for the shared Nitro host in the next PR.

package/ — the binding, no protocol logic left

• HybridEcr17Client maps the Nitro types onto the Kit's Ecr17Client. JS numbers go through toInt, so NaN or out-of-range values now throw instead of hitting undefined behaviour.
• NativeTransportAdapter exposes the Ecr17Transport HybridObject as a Kit Transport.
• On Windows, HybridEcr17TransportWindows wraps the Kit's WinsockTransport, keeping the dedicated connect thread.
• @padosoft/native-modules:
  • Ecr17.podspec is a single nitro_module(…, kit: "Ecr17Kit") call;
  • android/build.gradle applies nitro-module.gradle, and android.packageName moves to react-native.config.js;
  • the Android CMake finds the Kit with Node, and the vcxproj finds it in node_modules or ../kit.

💰 Money safety

RetryPolicy is untouched. The new Client.AFinancialCommandIsNeverResentAfterADrop test replays every financial command against a drop with autoReconnect on. In each case, the command goes out once and the socket is restored.

Deliberately breaking shouldRetryAfterReconnect (dropping safeToRetry) fails two tests.

⚠️ Not published on npm yet

@padosoft/native-modules (1.5.0) and @padosoft/expo (1.11.0) are installed from the padosoft GitHub Packages registry, like @padosoft/config:

• CI strips them where they aren't needed (scripts/strip-private-deps.mjs).
• android-build keeps them, so the GESCAT_NPM_TOKEN secret must be able to read padosoft packages.
• example-windows (npm) needs no registry config: npm resolves the dependencies of file:-linked packages from their own folder, which the root bun install fills.

@padosoft/ecr17-kit itself isn't published yet: changesets will publish it alongside the binding.

Changeset: minor

@padosoft/native-modules is a regular dependency of the binding and the Kit (it has no dependencies or peers), so apps get it automatically: no breaking change. The JS API is unchanged. On iOS, Expo apps add the Kit's config plugin (which uses @padosoft/expo, an optional peer of the Kit, because it peers on expo); bare apps list @padosoft/ecr17-kit as a direct dependency.

Verification

• ✅ Kit tests: 100/100 on macOS with AddressSanitizer and UndefinedBehaviorSanitizer, including 15 new client tests (cmake -S kit, which is also what cpp-tests now runs).
• ✅ iOS: the Expo example builds for the simulator, with no Ecr17/Ecr17Kit warnings:
  • expo prebuild -p ios: the Kit's plugin adds the pod;
  • pod install: nitro_module links Ecr17Kit through CocoaPods;
  • xcodebuild: BUILD SUCCEEDED.
• ✅ The binding's C++ compiles on host clang with -Wall -Wextra, and TS typecheck passes.
• ⏳ Not run here:
  • Android: the android-build job;
  • Windows (no toolchain here):
    • cmake -S kit -B build-win && cmake --build build-win --config Release && ctest --test-dir build-win -C Release;
    • the example-windows build and deploy;
  • a runtime smoke test against a terminal or fake terminal, on any platform.

The local Copilot review loop from AGENTS.md has not been run.

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