fix(ios): Fix iOS build with new architecture enabled

[momomuchu]

Fixes issue where iOS build fails with "RNTfliteSpec.h file not found" when React Native new architecture (TurboModules) is enabled.

Changes:

1. Podspec: Merge pod_target_xcconfig instead of overwriting to preserve TensorFlow Lite settings when new architecture is enabled
2. Podspec: Add RCT-RCTFabric dependency for Fabric support
3. Podspec: Remove duplicate CLANG_CXX_LANGUAGE_STANDARD entries
4. iOS: Update RNTfliteSpec.h import to use correct path format (<RNTfliteSpec/RNTfliteSpec.h> instead of "RNTfliteSpec.h")

The issue was caused by:

• pod_target_xcconfig being redefined instead of merged, losing TensorFlow Lite preprocessor definitions
• Incorrect header import path for Codegen-generated spec file

Resolves: #87

[momomuchu]

ref issue: #87

[efstathiosntonas]

I think you should also add this:

node_modules/react-native-fast-tflite/ios/Tflite.mm (+1 -1)
    57  {
    58 -    return std::make_shared<facebook::react::NativeTfliteSpecJSI>(params);
    58 +    return std::make_shared<facebook::react::NativeRNTfliteSpecJSI>(params);
    59  }

The TurboModule export now returns facebook::react::NativeRNTfliteSpecJSI, matching the actual JSI class generated in RNTfliteSpec. This resolves the “No member named NativeTfliteSpecJSI” error.