fix(ios): make event emit() templates compatible with RN 0.85+

[1kuko3]

Summary

React Native 0.85 (shipped in Expo SDK 56) changed facebook::react::SharedEventEmitter from shared_ptr<const EventEmitter> to shared_ptr<EventEmitter> (const dropped). RCTViewComponentView still holds _eventEmitter as SharedViewEventEmitter (shared_ptr<const ViewEventEmitter>), so the implicit conversion from shared_ptr<const ViewEventEmitter> to the new non-const SharedEventEmitter no longer compiles — shared_ptr won't strip const implicitly.

This PR templatizes the holder parameter on each event's emit() so the type is deduced from the call site. The static_pointer_cast<Emitter const>(...) body works unchanged for both old and new RN versions. No call site changes are needed because the second template parameter is deduced.

We hit this downstream when integrating @lugg/maps with Expo SDK 56 / RN 0.85.3 and have been carrying it as a patches/ override.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Test Plan

• Compiled the package against RN 0.85.3 (Expo SDK 56) in our consumer app — previously failed with const-conversion error on _eventEmitter, now builds clean.
• example/bare still on RN 0.83.0 — backward-compatible: the templated holder deduces to the old SharedEventEmitter and behaves identically.

Screenshots / Videos

N/A — C++ header-only change.

Checklist

• I tested on iOS
• I tested on Android (no changes — Android dispatches events from Kotlin)
• I tested on Web (N/A)
• I updated the documentation (not needed — internal C++ signature, not a public API)