Fix: enable React Native New Architecture support on iOS

[Axster]

🔍 Summary

Please provide a concise description of what this PR does and why.

• What did you change?

• Updated native iOS module declarations and imports to ensure compatibility with the New Architecture in React Native. Also made minor Android updates for consistency.

• Why is this change necessary?

• Without these changes, the library does not work properly under the New Architecture: iOS fails to expose the module methods due to the missing inheritance from RCTEventEmitter.

🛠️ Changes

• Replaced NSObject with RCTEventEmitter in StepCounter interface (iOS)
• Updated imports to include <React/RCTEventEmitter.h> for iOS
• Removed legacy bridge property and unused imports
• Updated package.json main field from lib/commonjs/index.js to lib/module/index.js
• Added @ReactModule import in Android module

🔗 Related Issue

this PR does not close any issue

✅ Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (backwards-incompatible)
• Documentation update
• Chore / Refactoring

📋 Checklist

• My code follows the repository’s style guidelines
• I have added tests covering my changes
• I have run yarn lint and yarn test locally with no failures
• I have updated the README or relevant documentation
• I have provided version and environment details if applicable

🚀 How to Test

1. git checkout <this-branch>
2. yarn install && cd example && yarn install
3. yarn build
4. yarn test
5. Example Usage:

   import {
     isSensorWorking,
     isStepCountingSupported,
     parseStepData,
     startStepCounterUpdate,
     stopStepCounterUpdate,
     type ParsedStepCountData,
   } from '@dongminyu/react-native-step-counter';
   // …

📸 Screenshots (if applicable)

If your change adds UI or visual output, include before/after screenshots or GIFs.

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