feat(config): add runtimePackageName to IConfigPlatform

[Copilot]

Matches IConfigPlatform proposed runtimePackageName for the NativeScript CLI to support custom configured runtime packages (for usage with different NAPI/engine combinations).

Changes

• packages/core/config/config.interface.ts — adds runtimePackageName?: string to IConfigPlatform, making it available on all platform sections (ios, android, visionos) via inheritance

Usage

// nativescript.config.ts
export default {
  android: {
    runtimePackageName: '@nativescript/android-quickjs',
  },
  ios: {
    runtimePackageName: '@nativescript/ios-hermes',
  },
} satisfies NativeScriptConfig;

ref: NativeScript/nativescript-cli#6039