fix(ios): resolve Xcode compiler warnings

[ngocdevv]

Summary

• Add non-empty descriptions to the gesture-handler @param documentation.
• Make the documented parameter names match the actual sender parameters.
• Explicitly convert the Fabric command's NSInteger page argument to the component's int storage type.

Problem

Xcode reports documentation warnings for empty or mismatched @param entries, plus an implicit 64-bit-to-32-bit conversion warning in setNativePage:.

Fix

The comments now document the correct parameters, and the page assignment uses an explicit static_cast<int>. The Fabric command is declared as Int32, so the conversion matches the command's existing type contract while making the native boundary explicit.

Testing

Compiled RNPDFPdfView.mm with Apple Clang from Xcode 26.6 using the CocoaPods-generated response file, React Native Fabric headers, iOS Simulator 26.5 SDK, and the target's warning settings (including documentation and 64-to-32-bit conversion warnings). The compile completed with no diagnostics.

Closes #1023.